why atonement

Why do we need atonement? From The New Bible Dictionary:

The need for atonement is brought about by three things, the universality of sin, the seriousness of sin and man’s inability to deal with sin. The first point is attested in many places: ‘there is no man who does not sin’ (1 Ki. 8:46); ‘there is none that does good, no, not one’ (Ps. 14:3); ‘there is not a righteous man on earth, who does good and never sins’ (Ec. 7:20). Jesus told the rich young ruler, ‘No one is good but God alone’ (Mk. 10:18), and Paul writes, ‘all have sinned and fall short of the glory of God’ (Rom. 3:23). Much more could be cited.

The seriousness of sin is seen in passages which show God’s aversion to it. Habakkuk prays ‘Thou who art of purer eyes than to behold evil and canst not look on wrong’ (Hab. 1:13). Sin separates from God (Is. 59:2; Pr. 15:29). Jesus said of one sin, blasphemy against the Holy Spirit, that it will never be forgiven (Mk. 3:29), and of Judas he said, ‘It would have been better for that man if he had not been born’ (Mk. 14:21). Before being saved men are ‘estranged and hostile in mind, doing evil deeds’ (Col. 1:21). There awaits the unrepentant sinner only ‘a fearful prospect of judgment, and a fury of fire which will consume the adversaries’(Heb. 10:27).

And man cannot deal with the situation. He is not able to keep his sin hidden (Nu. 32:23), and he cannot cleanse himself of it (Pr. 20:9). No deeds of law will ever enable man to stand before God justified (Rom. 3:20; Gal. 2:16). If he must depend on himself, then man will never be saved. Perhaps the most important evidence of this is the very fact of the atonement. If the Son of God came to earth to save men, then men were sinners and their plight serious indeed.