Is "sin boldly" considered by Lutherans to be an infallible statement by Martin Luther? I don't think I am without sin. But I believe that all things are possible with God's grace including avoiding sin. Even though there have been many times that I have fallen short and sinned, there were also many times that, by the grace of God, I was able to resist the temptation to sin. And I believe that I must continue to seek God's grace to help me to avoid temptation and sin. That's not the same as believing that I must "sin boldly" and go out of my way to sin in order to please God. The part in the Lord's prayer that says "lead us not into temptation" or more literally, "let us not fall into temptation" would be a pointless uterance if it were not possible to avoid sin and temptation. Avoidance of sin and temptation is impossible for us without God's grace, but with God's grace it is possible. And if it's possible with God's grace to avoid sin some of the time, then it's also possible with God's grace to avoid sin all of the time. I just haven't arrived at that point yet.