The word "agape" received a broader usage under later Christian writers as the word that specifically denoted Christian love or charity (), or even God himself. The expression "God is love" (ὁ θεὸς ἀγάπη ἐστίν) occurs twice in the New Testament: 1 John . "Agape" was also used by the early Christians to refer to the self-sacrificing love of God for humanity, which they were committed to reciprocating and practicing towards God and among one another (see "kenosis"). This understanding is built upon the foundational Hebrew concept of Chesed, or the lovingkindness of God, which is taught throughout the Old Testament.