Abstract
Jesus taught we always live out what is in our heart. Our life is primarily directed by the deeply submerged core beliefs, which may often be very different from what we say we value or believe. One key component of inner formation is changing our core beliefs, with God's grace, and thus reducing the willing-doing gap. In the article, after identifying the problem, and highlighting Jesus’ focus on inner or heart formation, a basic overview of the concept of a belief is presented. Then ten principles or features about core beliefs and formation are proposed and clarified, followed by some implications for practice.