What does it mean to have faith in the heart according to the Bible?

In the biblical context, to have faith in the heart signifies an internal transformation brought about by the Holy Spirit, where faith is not merely intellectual assent but involves trust and reliance on God (Romans 10:9). This faith leads to a genuine recognition of our own sinfulness and a belief in Christ's atoning work. Such heart faith is evidenced by a life that confesses Jesus as Lord and seeks to live in accordance with His teachings. It reflects a relationship with God rather than a mere adherence to rules or doctrines.