Secular psychologists operate on a biopsychosocial model of human development and behavior. This model proposes humans develop and operate according to biological, psychological, and social influences. Accordingly, we are products of our biology and environment, both bearing equal importance.
In more recent years, psychologists have begun recognizing that our spirituality impacts our lives, but have yet to say it is imperative for life. While the traditional psychological theories and models that are based upon naturalism are insufficient from a Christian worldview, not all of secular psychology is wrong. Indeed, there are many helpful and positive aspects of psychology to consider, which is why there is a need for integration.
The successful integration of psychology and Christianity has long been a passion of mine. However, I tread carefully on this topic. As a secularly trained doctor, I recognize my shortcomings in relation to the integration of theology and psychology. The nuances of the Biblical Counseling, Integrationist, and Christian Psychology models have been extensively evaluated by more notable minds than mine.
I will not speak to any one particular model, but provide key points to consider when integrating psychology and Christianity. These points, I believe, fall on the continuum between the Integrationist and Christian Psychology models.