I think you should think about your inability to judge sin for what it is and hold those who do it responsible. This does not go against Christ's teachings. If it did he would not tell us "fruits" analogy (and many other things he said). I am not going to be anybody's judge, but you shouldn't follow leaders who have bad fruit, they will steer you wrong, this requires judgement, good judgement. You are trying to make "thou shalt not judge into the 11th commandement, it isn't one.
No one here is actually defending Constantine, that was not the premise of the original question.
Coulda fooled me, I still see RC sources calling him "Holy", on this thread if I'm not mistaken.
How do you account for St. Paul? He was directly and indirectly responsible for a lot of atrocities - including the stoning of St. Stephen. St. Paul repented and followed Jesus. His works bore good fruit as we all know. Do you condemn St. Paul for his acts previous to his conversion? How do you (or anyone for that matter) know what was in Constantine's heart and soul before he converted at the end of his life?
Paul did many evil things before he was a Christian, so dod Constantine. The difference, which you refuse to see apparently, is what they did after they claimed to have been converted. Paul proved by his actions he was, Constantine continued committing his evil acts.
We can condemn the acts, but not the man.
You can't condemn him because of his place in your church's history. The RC church does try very hard to condone his actions as well. (this thread is proof of that).
I ask you, how do you know that Constantine bore bad fruit after his conversion? Have they found new evidence (like more old scrolls) in the past few weeks?