Some people have the spiritual gift of teaching and/or edification, although these people would have a higher responsibility because of teaching such an important subject as our very own faith. By grace we are saved, and we should strive for perfection, even though we will never be perfect until we are either raptured or leave this life.
Blaming something outside of yourself is a form of weakness, and so taking responsibility for everything shows an inner fortitude. The Bible says we were all sinners, but Christ died for us anyways. Regardless if you think sin is inevitable or not, if you believe in the resurrection and strive to avoid sinning, then you're good to go.
I believe it's what belief you are congruent with at the time. To one man something is sin, to another it is not.
Romans 14 1-11 says
Accept other believers who are weak in faith, and don’t argue with them about what they think is right or wrong.
2For instance, one person believes it’s all right to eat anything. But another believer with a sensitive conscience will eat only vegetables.
3Those who feel free to eat anything must not look down on those who don’t. And those who don’t eat certain foods must not condemn those who do, for God has accepted them.
4Who are you to condemn someone else’s servants? Their own master will judge whether they stand or fall. And with the Lord’s help, they will stand and receive his approval.
5In the same way, some think one day is more holy than another day, while others think every day is alike. You should each be fully convinced that whichever day you choose is acceptable.
6Those who worship the Lord on a special day do it to honor him. Those who eat any kind of food do so to honor the Lord, since they give thanks to God before eating. And those who refuse to eat certain foods also want to please the Lord and give thanks to God.
7For we don’t live for ourselves or die for ourselves.
8If we live, it’s to honor the Lord. And if we die, it’s to honor the Lord. So whether we live or die, we belong to the Lord.
9Christ died and rose again for this very purpose—to be Lord both of the living and of the dead.
10So why do you condemn another believer? Why do you look down on another believer? Remember, we will all stand before the judgment seat of God.