What the Bible says about Jesus Christ's Claim on Human Conduct
(From Forerunner Commentary)
Jesus made an atonement for sin that places a claim on human conduct. Hebrews 1:3 dogmatically informs us He atoned for sin by Himself. No animal was involved. No other man or angel did it. The bulk of educated humanity knows this truth but ignores what it means for the profitable use of a person's life. Most shrug off that His sacrifice opens the door to God's offer of salvation to those He calls. Though many may seem convicted of the fact of Jesus' sacrifice, they apparently have no faith that the authority of the Father guarantees the efficacy of His sacrifice.
Conclusion: Sin continues because most people fail to take Christ's sacrifice and its ramifications seriously.
John W. Ritenbaugh
Why Hebrews Was Written (Part Ten): Christianity's Claims