'Heart' in the Bible

to Timothy, my beloved son: Grace, mercy, and peace [inner calm and spiritual well-being] from God the Father and Christ Jesus our Lord.

I remember your sincere and unqualified faith [the surrendering of your entire self to God in Christ with confident trust in His power, wisdom and goodness, a faith] which first lived in [the heart of] your grandmother Lois and your mother Eunice, and I am confident that it is in you as well.

Run away from youthful lusts—pursue righteousness, faith, love, and peace with those [believers] who call on the Lord out of a pure heart.