Our Team

Kevin Nieman, Ph.D., LMFT, EMDR, Director

Dr. Kevin Nieman Ph.D. LMFT is the owner and founder of Cornerstone. He graduated from Harding University with a bachelor’s in business management. From there he obtained his master’s from Harding’s Marriage and Family Therapy program and then continued his studies in this field at the University of Louisiana at Monroe where he received his doctorate degree. Dr. Nieman operated a private practice in West Monroe, La for approximately 5 years before transferring the counseling center to Tulsa, OK in 2009. He is a member of the American Association of Christian Counselors (AACC) and is an AAMFT Approved Supervisor for Marriage and Family Therapists. Dr. Nieman is also certified in EMDR (Eye Movement Desensitization and Reprocessing). He is currently in the process of becoming AASECT certified which is the leading certification for sexual health practitioners.

Dr. Nieman has a passion for helping hurting people find hope and healing. His areas of specialty and interest include marriages in crisis, differentiation and self-worth development, and consulting. His consulting practice Dr. Kevin Nieman combines his background in business management with the relational expertise of his MFT training. This practice includes work with business leaders, top tier management, CEOs and professional athletes. Dr. Nieman has two overriding beliefs that help guide his work. First, he will love you unconditionally and secondly, he will accept you unconditionally for who you are. You are either a son or daughter of the Most High, you have incredible value and worth. Dr. Nieman believes strongly in helping others see themselves as Christ sees them, in order to bring about true heart transformation.

Monroe (Roe) is Dr. Nieman’s therapy dog that will join him for sessions from time to time. She loves people and is always excited to greet everyone that enters the office. She has a gentle spirit, enjoys belly rubs and kisses, and loves to show off a trick or two.

Dr. Nieman is married to Lindsey Nieman, M.A. who is also a provider at Cornerstone. Together they have two beautiful boys. Dr. Nieman enjoys relaxing with his family, camping, woodworking and he is also an avid Green Bay Packer fan.

Lindsey Nieman, M.A., RDN, LD LMFT

Lindsey Nieman, M.A. RDN LD LMFT is a staff therapist and dietitian at Cornerstone. She earned her Master of Arts in Marriage and Family Therapy and an undergraduate degree in Business Management from the University of Louisiana at Monroe (ULM). She also has an undergraduate degree is Nutrition and Dietetics from Louisiana Tech University. Lindsey finished her dietetic internship through the University of Oklahoma Health Science Center. She is currently finishing her dissertation for her Doctor of Natural Medicine Ph.D. from Quantum University. She is a registered dietitian as well as a Licensed Marriage and Family Therapist and a Neurofeedback practitioner certified with BCIA. Lindsey is also a certified in Emotional Freedom Technique and energy tapping practitioner. She uses this certification along with her NES health bioenergetics assessments to help clients find more precise healing. Lindsey is a member of the Institute of Functional Medicine and has completed all coursework offered through this organization. 

Lindsey is passionate about helping individuals achieve a healthy lifestyle physically, emotionally, mentally and spiritually. She combines her knowledge from the nutrition perspective with her Marriage and Family Therapy training to provide her clients with a more complete approach to health. Lindsey directs the BrainHealth program and integrates nutrition and brain health principles in her client care. Lindsey is also in charge of the functional and integrative health program and aims to assess clients needs on all levels of health and help direct them toward therapies that match their needs. 

Lindsey is married to Dr. Kevin Nieman, founder and director of Cornerstone and together they have two beautiful boys. Lindsey enjoys spending time on their land raising chickens and gardening to provide fresh, nutritious food for her family. She also enjoys exercising, spending time in nature, hiking, camping and cooking.

Paige Tallent, LPC

Paige Tallent, MHR, LPC earned a Bachelor of Science in Psychology from Northeastern State University and a Master of Human Relations from the University of Oklahoma. Paige has worked in the counseling field since 1999 serving youth, adults and seniors. Paige is a Nationally Certified Counselor; a Licensed Professional Counselor in Oklahoma; a Board Approved Supervisor for candidates seeking counseling licensure, and an ordained minister.

Paige is committed to helping individuals, couples and families, find their identity in Christ and their calling as healthy children of God. Paige specializes in trauma recovery; improving relational dynamics within couples and families; encouraging single parent families to heal and excel. Paige is dedicated to suicide prevention and implemented a free suicide prevention service program, Because of Hanah, in Washington County.

Paige is passionate about her family, travel, nature, antique collection and restoration and the art of friendship.

Deidra Nickel, LPC

Deidra Nickel earned her M.A. in Marriage and Family Therapy from Southern Nazarene University. She is a registered Licensed Professional Counselor with the State of Oklahoma.

She has a passion for helping families, especially women, determine who they are in Christ and their purpose as they navigate life’s struggles and hardships. Deidra is also trained in EMDR.

Deidra enjoys singing at church, spending time with her family and friends, classical music, and riding with her husband on his Harley.

Melanie Walker, M.S. LPC

Melanie Walker, M.S., LPC earned a Bachelor of Science in Human Services and a Master of Science in Clinical Mental Health Counseling from Evangel University in Springfield, MO. Melanie is a Nationally Certified Counselor and Licensed Professional Counselor in Oklahoma. She holds certificates in EMDR (Eye Movement Desensitization and Reprocessing), DBT (Dialectical Behavior Therapy), Gottman Marriage therapy and is an ordained minister. Melanie is a member of the American Psychological Association (APA) and the American Association of Christian Counselors (AACC).

Melanie is dedicated to the empowerment of individuals and families in discovering their worth and potential in Christ. She is passionate about walking the journey of identification, healing, and growth with clients. Melanie strives for collaboration in a trusting, respectful environment. She believes her responsibility is to listen, educate, guide supply tools, and gently confront client’s belief systems. Melanie specializes in anxiety, depression, grief and loss, life transitions, marriage and family, PTSD, parenting and trauma.

Melanie enjoys spending time with her husband, Rick, of 38 years and their ever expanding family. She also enjoys biking, reading, and traveling.

Alissa Scharf, M.S., LMFT

Alissa Scharf earned her B.S. in Psychology from The University of Science and Arts of Oklahoma in 2014 and her M.S. in Marriage and Family Therapy from Oklahoma Baptist University in 2017. She is a Licensed Marriage and Family Therapist with the State of Oklahoma.

Alissa has a passion for helping families, individuals, and couples achieve their goals and improve their relationships.  She enjoys helping her clients find their true identity in Christ.  Alissa has experience treating trauma, anxiety, depression, ADHD, and relational issues.  Alissa is also trained in Medical Family Therapy, CAMS (suicide treatment and prevention), and Prepare & Enrich (a premarital and marital curriculum).

Alissa enjoys serving with her church, spending time with her family and friends, and traveling to new beaches with her husband.

Madeline Dozier, M.A., LMFT Candidate

Madeline Dozier, M.A. is a registered Licensed Marriage and Family Therapist Candidate.  She earned her Master of Arts in Marriage and Family Therapy from Southern Nazarene University.  She received her Bachelor of Arts degree in Psychology with a minor in Sociology from Oral Roberts University (ORU).

Madeline is an EMDRIA approved EMDR certified therapist.  She is also certified in SYMBIS, a premarital curriculum.  In addition, she is pursuing her certification as an AASECT approved sex therapist.  She is a member of the American Association for Marriage and Family Therapy (AAMFT). 

Madeline is passionate about helping individuals, couples, and families find healing in their past by regaining their voice.  Through that process she believes they will be able to rebuild trust within their relationships, restore hope, and find their true identity in Christ so that they may fulfill their God given purpose.

Madeline’s areas of specialty and interest include premarital, couples, trauma recovery, sexual related issues, and self-worth development.

Madeline enjoys spending time with her friends and family, running, reading and traveling.

Kristen Snyder, M.A., LMFT Candidate

Kristen Snyder, M.A. is a registered Licensed Marriage and Family Therapist Candidate at Cornerstone. She earned her Master of Arts in Professional Counseling at Oral Roberts University in Tulsa, OK. She received her Bachelor of Arts degree in Communication with a secondary major in Psychology also from Oral Roberts University. Kristen is recognized by the Oklahoma Department of Mental Health and Substance Abuse Services as a Behavioral Health Wellness Coach.

Kristen is passionate about helping people discover a more authentic way of living. She believes in addressing the root of problems in order to create lasting change. In her experience, Kristen has found that people are often controlled by fear, shame, and anxiety that inhibits them from living freely. She enjoys patiently walking with clients through the therapeutic process to help them become more driven by love, grace, and peace. Kristen seeks to not only understand people on the individual level, but to also take into account the system around them, the patterns they get stuck in, and their relationship dynamics. Kristen believes that the ultimate agent of change in therapy is the Holy Spirit working in clients’ hearts and minds.

Kristen’s areas of specialty and interest include premarital counseling, marital conflict, anxiety, self-worth development, trauma recovery, and communication issues.

Kristen and her husband, Bryce, have been married since 2015. They describe their marriage as playful, committed, and empowering. Kristen enjoys exercising, reading, traveling, and spending quality time with friends and family.

Gregg Nelson, LPC Candidate

Gregg Nelson is currently an LPC Candidate staff therapist here at Cornerstone. He will then work toward obtaining his licensure as a Licensed Professional Counselor. He graduated in 2019 from Liberty University with his Professional Counseling degree. He received his Bachelors of Arts Degree in Biblical & Theological Studies from Regent University in 2012. He holds specialized certification in the field of Spiritual Care in Crisis Intervention from the International Critical Incident & Stress Foundation, Inc. and is involved with numerous Critical Incident Stress Management (CISM) teams across the country. He is a certified Gottman Seven Principles Program Leader, is an ordained minister, serves on the Board of Directors of numerous nonprofit organizations as a consultant and is a member of the American Association of Christian Counselors (AACC).

Gregg is dedicated to individuals, couples and leaders to help Educate, Equip, Encourage and Empower their lives, relationships and careers. He works along side his clients to find hope and healing through knowing who they are in Christ and discovering their identity and value in Him. Gregg’s areas of specialty include spiritual, relationship, leadership, premarital, couples, loss, grief, stress and crisis/trauma issues.

Gregg enjoys traveling, networking, volunteering, reading, going to his son’s swim meets and spending time with friends & family.

Donald (D.A.) Myers, M.S., LPC Candidate

Donald (D.A.) Myers, M.S. is a registered Licensed Professional Counselor Candidate.  He earned his Master of Science in Counseling Psychology from Southern Nazarene University. He received his Bachelor of Arts degree in Psychology from Southern Nazarene University as well. Donald performed his internship at Cornerstone Christian Counseling where he continues to work.

D.A. is passionate about helping couples, individuals and families find hope and healing through the power of defining our identity in Christ. When we are able to tear away the lies that try to latch onto our identity, we can truly define who we are and more importantly, WHOSE we are. When we identify and put words to the cycles we constantly find ourselves in, we can break into the cycle and start to produce new behaviors that respect and show love to those around us and to ourselves.

D.A. enjoys spending time with his wife and three children, reading, and drinking coffee.

James Simmons, M.A., LPC Candidate

James Simmons is currently an LPC Candidate staff therapist here at Cornerstone. He received his Bachelors of Arts degree in Psychology from Oklahoma State University in 2010. Later; earned his Masters of Arts in Counseling Psychology from Southern Nazarene University. James has served as an intercity minister, youth minister and currently serves as a young adult minister at a local church in Tulsa, OK.

James has a passion for helping people find hope and healing. James is certified as a SYMBIS marriage assessment facilitator and has a passion for helping marriages thrive in the grace and love of Jesus Christ. James’ approach to counseling is formed under the grace and truth from Jesus Christ. James aims to assist client’s come to an understanding of their own situation and take responsibility for their own process. He operates from an eclectic approach of counseling and specifically works within Cognitive Behavioral Therapy, Solution Focus Therapy and Emotion Focused Therapy.  James areas of specialty include premarital and marital counseling, communication skills, depression, anxiety, and spiritual issues. 

James enjoys getting to know people on a deep level; his hobbies include listening to different types of music, reading, watching movies and spending time with his family.

Becky Weathers, Office Manager

Becky Weathers is our office manager and has worked with us for over 6 years.  Before coming to Cornerstone, she worked in the health insurance industry for nearly 27 years and then in the medical industry for a little over 3 years.  Becky loves working with people and hopes to make a positive difference each day.

Becky and her husband have been married for over 30 years and have raised 3 beautiful daughters.  They also have two sons in law and are now the proud grandparents of 4 grandchildren.  In her spare time, Becky enjoys traveling, spending time with her family and especially being a Nana to her 2 grandsons and 2 granddaughters. 

Sonia Marshall CYT, Relax & Renew® Trainer

Sonia is a Yoga Instructor and Graphic Artist. She earned her 200 hr. YTC in Hatha Yoga from Yoga Spirit Academy in Tulsa, earned a Bachelors Degree in Commercial Art from Oral Roberts University, and in 2015 she was certified as a Relax & Renew@ Trainer in Dallas TX, with Judith Lasater.

She began practicing yoga to manage chronic back pain, stress and anxiety, and through regular practice she discovered how yoga can help to heal the body and mind. From her personal experience, she is inspired and passionate about sharing the practice of yoga with others.

Sonia teaches with a gentle approach, with a focus on body awareness.

Sonia and her husband have been married for 18 years. She has lived in Tulsa for 26 years and enjoys camping with her husband and their two dogs, Stella and Hadi. She loves experimenting with new recipes, traveling, and music.

Connor Kelly, M.S., LPC Candidate

Connor Kelly is a registered Licensed Professional Counselor Candidate as well as a part of the front office staff at Cornerstone. He earned his Master of Science in Marriage and Family Therapy from Harding University. He received his Bachelor of Business Administration degree in Business Management from Harding University.

Connor is committed to walking alongside hurting individuals, couples, and families to find healing and hope through Jesus Christ. In his experience, when we are able to call out Satan’s lies for what they are, and begin to have grace and compassion for ourselves, true transformation can begin. Connor’s areas of interest and specialties include self-worth development, marital conflict, depression, anxiety, and trauma.  

Connor enjoys spending quality time with his wife and dog, traveling, watching movies, and all things Thunder basketball.

Megan Weathers

Megan Weathers is part of our front office staff. She has worked with us since April of 2020. Before coming to Cornerstone she was working as an Au Pair in Sydney, Australia. Megan loves to see the positive transformations in our clients during therapy. “God understands the cries of our hearts, even when they’re too deep for words.”- Romans 8:26

In Megan’s spare time she loves traveling, reading, watching movies and spending time with her family, friends and sweet dog, Nitro. One of Megan’s favorite things is being an aunt to her 2 nieces and 2 nephews.

Jamie Clayton, FMCHC

Jamie Clayton earned her Functional Medicine Health Coach Certification from the Functional Medicine Coaching Academy in 2020.  She also serves as a Neurofeedback Technician within the Cornerstone Neurofeedback Brain Training Program since 2018. 

Jamie is passionate about empowering her clients by using positive psychology techniques to harness their strengths in achieving their personal health goals.  She walks alongside each client in their personal health journey to overcome life challenges and promote optimal wellness through nutrition and positive lifestyle changes.  Jamie can also work with Registered Dietician, Lindsey Nieman and other Licensed Therapists at Cornerstone as part of your collaborative healthcare team. 

Jamie enjoys outdoor activities such as running, hiking, kayaking and camping with her family and friends. 

Monica Maris, LMSW

Monica received her Associates of Arts in Bible from Crowley's Ridge College in Arkansas. After deciding that she wanted to pursue further education in the area of mental health and relationships, she obtained her Bachelor of Social Work at Northeastern State University in Tahlequah, Oklahoma. She then obtained a Masters of Social Work at the University of Oklahoma Health Science Center. 

Monica has four children and has spent the last few years as a stay-at-home mom. She came to Cornerstone this year as a neurofeedback technician because she is excited about neurofeedback and wants to be a part of this growing field along with the benefits it provides.

In her free time, Monica likes to spend time with her family and church.