What is the most sin someone has ever committed in a lifetime?
This said, even the absolute evilness of one sin is enough to separate one from the living God for eternity. Something many don't consider is just how evil just one sin actually is. Even this we can't fully describe in an answer. And we have to be cautious not to compare ourselves to others that may have sinned more than us too. God doesn't grade your eternity on a curve; just because you may have sinned less than someone else doesn't mean you'll enter the new heavens and the new earth and they won't.
All sin is rebellion against God (Psa. 51:4). We are called upon to literally hate sin and to be revolted by it (Rom. 12:9-10; Jas. 4:8-9). It should bring us to great sorrow and repentance. However, though the utter grossness of even one sin is far beyond full description, God's love for his people is even more-so beyond full expression. Paul simply says, "God shows his love for us in that while we were still sinners, Christ died for us" (Rom. 5:8; John 15:13). Considering how much God hates sin (Prov. 8:13; Rev. 2:6) and sinners (Lev. 26:30 [Lev. 26:28-39]; Psa. 5:4-5; 11:5-7; Prov. 6:16-19; Rom. 9:13) Paul's statement is a miraculous truth. One could take a lifetime to unpack all this one verse entails. Those in Christ are far more forgiven than they could ever imagine now and for all eternity. One day his people shall see him face to face. What a Day that will be.
Dr. Joseph R. Nally, Jr., D.D., M.Div. is the Theological Editor at Third Millennium Ministries (Thirdmill).