Galatians 3:13
NKJV - 13 Christ has redeemed us from the curse of the law, having become a curse for us (for it is written, "Cursed is everyone who hangs on a tree").
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No man, except Jesus Christ has ever been able to live a completely sinless life. The penalty for ANY sin is eternal damnation. Since the way to eternal Life was to be free of any sin, and no man could achieve that, sacrifices were made with animals. However those sacrifices were only temporary. Jesus came, lived a sinless life and sacrificed himself for ALL humanity, removing the curse of the law for those who accept him as Lord and Savior.