About Us

We are a group of Christians who have chosen the vocations of mental health professionals, including psychiatrists, psychologists and psychotherapists. Along with various supporters, we are like-minded professionals in that we desire to glorify God by helping people find not only relief and healing from mental health ailments, but also healing in their spirit that can only be found in reconciliation with God through receiving Jesus Christ.


To promote recovery and freedom from mental health issues through raising awareness and providing education about the integration of the message of Jesus Christ with comprehensive healthcare resources (Matthew 11:28, John 8:36).

OHF recognizes the need for an effective, holistic approach for individuals and families affected by psychiatric problems. OHF is led by professional mental health practitioners who recognize that mental disorders result from multifactorial reasons (biological, psychological, sociological, spiritual). OHF is committed to be a resource regarding attainment of freedom from psychological suffering through the integration of the Gospel message of Jesus Christ with mental health services (Isaiah 61:1-3).


Hearts healed, souls saved, aspirations attained, God glorified.

OHF is compelled by a vision that persons who experience mental suffering will:

  • Experience life eternal through an encounter with God through Jesus Christ (John 3:15-16).

  • Receive a deeper understanding of life’s purpose, including the reasons and resources for life's challenges (Romans 8:28).

  • Witness the healing from mental problems through the combination of evidence-based psychiatry/psychology and the spiritual training in the Gospel especially when the existing proven methods insufficiently mitigate symptoms (Luke 9:6,11).

  • Experience restoration of mental health, academics, finances, interpersonal relationships, career goals, and thus gain the ability to give back to the community by being agents of healing themselves (Luke 8:39).

What We Believe

    Personal Statement of Faith and Commitment to Personal Growth

    Each of us agrees with this personal statement of faith.

    • I was born a sinner, separated from God. (Rom 3:23)
    • I had no choice but to face inevitable life problems, spiritual and physical death, and eternal condemnation (Gen 3:19, Eph 2:1-2)
    • Jesus, as the Christ, is the only answer for my final deliverance and he is the only hope for this world struggling with pain and suffering. (Matt 16:16, Rom 8:2, 1 John 3:8)
    • Saved not by my works, I became a child of God because His Spirit planted faith in my heart to believe that Jesus’ death and resurrection paid for ALL my sins. (John 3:16, John 1:12, Rom 10:10)
    • With this new identity of Christ-in-me, I received all His covenant promises to experience on earth before we reach our final eternal home. (Matt 6:33, Eph 3:16-21)
    • Praises to God who desires to use me “to be His witness to all people”. (Phil 1:6, Acts 1:8, Acts 22:15)

    In addition to our commitment to our ongoing development as mental health professionals, we are committed to growing in our relationship with Jesus Christ. We receive regular spiritual nourishment through weekly worship and the teaching from the Word of God through various pastors.

    Inspiration of Oak Health Foundation

    Our passion is for people and their need for Jesus. Throughout our adult lives we each have also served as volunteer leaders and have years of experience in various ministries with children, youth, and young adults, as well as campus ministries and overseas missions.

    But with the opening of Oak Health Foundation, we are now able to merge both the professional skills and a capability to serve in the mental health field that God has granted us, along with our passion for people to find complete restoration through a relationship with Jesus Christ. We believe He’s called us to use this career as a vehicle to spread His Gospel message and bring healing to this hurting world.

    OHF is a tangible place to mobilize mental health missions with the vision to lead everyone to experience Isaiah 61:1-3.

    Professional Credentials

    • Esther Park, D.O.

      • Dr. Park is a board-certified child, adolescent and adult psychiatrist. Her undergraduate studies were completed at UCLA. She trained to be a physician at Kirksville College of Osteopathic Medicine. During the first year of her family medicine residency training program, she realized her calling was really in the mental health field. Dr. Park completed her psychiatric training at the LAC/USC Medical Center and has more than seventeen years of outpatient clinical experience treating children and adults.

    • Mijin Park, PsyD

      • Dr. Mijin Park is a licensed clinical psychologist, a graduate from The Chicago School of Psychology. She provides psychological services for clients of all ages. She particularly enjoys working with adolescents along with providing effective parenting skills. Her expertise is also in the area of intergenerational conflicts within multi-cultural families. Dr. Mijin also provides psychological assessments in areas such as ADHD, executive functioning, and emotional dysregulation.

    • Steven Calleros, MD

      • Dr. Calleros is a board certified psychiatrist who specializes in treating children and adolescents. He earned his MD at Drexel University and did his psychiatry residency at LAC/USC Medical Center. He's been treating clients in an outpatient setting for over 10 years. Dr. Calleros also speaks Spanish and is a husband and father.


    Here’s what others say about the Lead Team of Oak Health Foundation.

    • From Colleagues and Pastors

      • "Dr. Esther Park and her team have been an invaluable and indispensable resource to our congregation and local community. We are thankful to God for their sincere commitment not only as mental health providers but also as a fellow believer in the Lord Jesus Christ. Just as their expertise and effectiveness have been demonstrated with the careful way staff have cared for our referrals, so too has been their spiritual leadership evidenced in the Bible Studies/community groups and larger community engagements they have facilitated with a focus on mental health. I consider Dr. Esther Park, as do other pastors of care in the Orange County region, as a critically important therapeutic and spiritual resource for the kind of gospel-centered ecosystem of care that we envision, pray, and hope for as a larger Christian community.” - Matthew Si, Pastor of Soul Care, Calvary Chapel Costa Mesa, Chaplain, 1st Marine Expeditionary Force (I MEF), United States Naval Reserve, Chaplain, Battalion 5, Orange County Fire Authority (OCFA)

      • "I have known and collaborated with Dr. Esther Park for approximately 10 years. She has always impressed me with her knowledge, professionalism, and insight into her clients. I have also worked closely with one of her colleagues, Dr. Mijin Park, who is both a talented clinician and a caring human being. Oak Health Center is my first referral for clients who can benefit from their services because I know they will receive exceptional, caring, individualized treatment from Dr. Park and her Team!” - Dr. Mariam A. Mott, Ph.D., Licensed Clinical Psychologist in private practice

      • “Dr. Esther Park and her team are an invaluable asset to the mental health field overall and to our community in Southern California in particular. With decades of combined experience as researchers and practitioners, the team at Oak Health Center serve as a robust, caring, seasoned group of healthcare providers. I could not recommend this clinic enough—and often do to friends, family, and students in the area. LA and Orange Counties, along with the surrounding areas, are blessed to have such a treasure in our midst.” - Dr. Richard S. Park, D.Phil / Assistant Professor of Theology & Ethics at Vanguard University

    • From Patients and Parents

      • “I appreciate how my doctor connects with me emotionally and spiritually."

      • “They help me realize what the proper diagnosis is which was the key to recovery, and now I am reaching my potential!”

      • “We are so grateful for you. We believe God provided you for our gals, and we are so thankful for your guidance, medical expertise, and care all along the way.”

      • “I can’t believe how different my life is now versus one year ago. Thanks to my treatment team, I can now look towards my future with hope.”