Grace
Grace (Hebrew ḥēn; Greek charis) is the unmerited favor and free, sovereign kindness of God toward undeserving sinners. It is not a reward for the worthy but a gift to the guilty, and it stands at the heart of the gospel — both God’s gracious disposition and his active power at work to save and transform.
Grace runs through the Old Testament. Noah "found favor in the eyes of the LORD" (Genesis 6:8); God chose Israel not for any merit but simply because he loved them (Deuteronomy 7:7–8); and the LORD revealed his own name to Moses as "merciful and gracious, slow to anger, and abounding in steadfast love" (Exodus 34:6).
Grace reaches its fullness in Christ: "the Word became flesh… full of grace and truth," and "from his fullness we have all received, grace upon grace" — for "grace and truth came through Jesus Christ" (John 1:14, 16–17). It is most clearly seen at the cross: "God shows his love for us in that while we were still sinners, Christ died for us" (Romans 5:8).
Salvation is therefore by grace from first to last: "by grace you have been saved through faith… not a result of works, so that no one may boast" (Ephesians 2:8–9); sinners are "justified by his grace as a gift" (Romans 3:24), and election itself is "by grace" and so not by works (Romans 11:6; Romans 5:20–21), ensuring God alone receives glory. Grace is also power for living: it is sufficient in weakness (2 Corinthians 12:9), "trains us to renounce ungodliness" (Titus 2:11–12), energizes service (1 Corinthians 15:10), and is the realm in which believers grow (2 Peter 3:18). Grace is the gospel’s heartbeat: God freely saving the undeserving in Christ.