The English word “atonement” derives from an Anglo-Saxon term which, practically speaking, signifies “a making at one.” Though the English term “atonement” is common to the Old Testament, it is found only once in the New Testament (Romans 5:11 KJV). There the original term katallage is better rendered “reconciliation” (ASV; cf. also 2 Corinthians 5:19). The Greek word denotes the “reestablishment of an interrupted or broken relationship” (F.W. Danker, et al. 2000. Greek-English Lexicon. Chicago: University of Chicago. 521).
In the biblical context, atonement has to do with the plan employed by the Lord to provide a way of salvation for sinful humanity by means of the redemptive mission of Christ. Here are the basic facts.
(1) God is a perfectly holy Being (Isaiah 6:3; Revelation 4:8); sin, therefore, is contrary to his very nature (James 1:13). As a truly holy Being, the Lord cannot ignore sin, or tolerate wickedness indefinitely, in any form (Habakkuk 1:13).
(2) Jehovah is also a God of justice. It is the very foundation of his rule (Psalm 89:14). Accordingly, some satisfaction for sin must be made. The principle is this: “The wages of sin is death” (Romans 6:23).
(3) If, therefore, man was to be redeemed, God would have to extend mercy (cf. Ephesians 2:4) in some fashion whereby divine justice could be satisfied. Exactly how was that to be achieved? A “death” would be required to remedy the problem (Hebrews 9:22).
(4) The solution is realized in the gift of Christ. Jesus lived the sinless life (John 8:29; Hebrews 4:15; 1 Peter 2:22), and therefore became qualified to function as a substitute offering on man’s behalf (cf. Hebrews 5:8-9).
Through Jesus’ death, Heaven’s requirement of justice is satisfied (see Isaiah 53:11; Romans 3:22ff). Hence, the atoning offering of the Son of God became available to all men (Isaiah 53:6; John 3:16; 1 Timothy 2:4; 2 Peter 3:9). (Note: The Calvinistic dogma of a “limited” atonement — only for an “elect” group, chosen before the foundation of the world — is quite erroneous.)
(5) Jesus is the author of eternal salvation to all who obey him (John 3:36; Romans 6:17-18; Hebrews 5:8-9). One is reconciled to God when he, through obedience, accepts Christ as his “atonement” offering.