'Heart' in the Bible

Watch out, brothers, so that there won’t be in any of you an evil, unbelieving heart that departs from the living God.

For the word of God is living and effective and sharper than any double-edged sword, penetrating as far as the separation of soul and spirit, joints and marrow. It is able to judge the ideas and thoughts of the heart.

let us draw near with a true heart in full assurance of faith, our hearts sprinkled clean from an evil conscience and our bodies washed in pure water.

For consider Him who endured such hostility from sinners against Himself, so that you won’t grow weary and lose heart.

Don’t be led astray by various kinds of strange teachings; for it is good for the heart to be established by grace and not by foods, since those involved in them have not benefited.