'Heart' in the Bible

See to it, my brothers, that no evil, unbelieving heart is found in any of you, as shown by your turning away from the living God.

For the word of God is living and active, sharper than any double-edged sword, piercing until it divides soul and spirit, joints and marrow, as it judges the thoughts and purposes of the heart.

Stop being carried away by all kinds of unusual teachings, for it is good that the heart be strengthened by grace, not by food laws that have never helped those who follow them.