Heart: According to the Bible, the heart is the centre not only of
spiritual activity, but of all the operations of human life.
"Heart" and "soul" are often used interchangeably (Deut. 6:5;
26:16; compare Matt. 22:37; Mark 12:30, 33), but this is not
generally the case.
The heart is the "home of the personal life," and hence a man
is designated, according to his heart, wise (1 Kings 3:12,
etc.), pure (Ps. 24:4; Matt. 5:8, etc.), upright and righteous
(Gen. 20:5, 6; Ps. 11:2; 78:72), pious and good (Luke 8:15),
etc. In these and such passages the word "soul" could not be
substituted for "heart."
The heart is also the seat of the conscience (Rom. 2:15). It
is naturally wicked (Gen. 8:21), and hence it contaminates the
whole life and character (Matt. 12:34; 15:18; compare Eccl. 8:11;
Ps. 73:7). Hence the heart must be changed, regenerated (Ezek.
36:26; 11:19; Ps. 51:10-14), before a man can willingly obey
The process of salvation begins in the heart by the believing
reception of the testimony of God, while the rejection of that
testimony hardens the heart (Ps. 95:8; Prov. 28:14; 2 Chr.
36:13). "Hardness of heart evidences itself by light views of
sin; partial acknowledgment and confession of it; pride and
conceit; ingratitude; unconcern about the word and ordinances of
God; inattention to divine providences; stifling convictions of
conscience; shunning reproof; presumption, and general ignorance
of divine things."