Why does the past matter then?

Rev Wright was a Marine and a Patriot. He has said some things (which were correct) about this country that were not accepted by white people. People now say that he WAS ok then, but he's a bad man now b/c of his remarks. If that's the case, why does anything that happens in the past matter? Wm. Ayers WAS a Weatherman, but now is a college professor. Is he good or bad?