This is an email I sent some time ago to a chance yahoo-group-acquaintance who was asking my advice (on the eve of her wedding!) about how to talk to her Christian relatives about Buddhist morality. I don't know if it really belongs here.
I see. Well, really Christianity and Buddhism are both all over the map about these issues -- we just don't hear much about the more fundamentalist Buddhists here in the West, but they exist, and they're perfectly capable of telling people they'll go to the hell realms for a zillion kalpas for stealing or having the wrong kind of sex or whatever. And of course Christianity insists, tho not all Christians listen to it, that all sins are forgiven, which means that the critical part of Christian practice is not following the DON'Ts perfectly, but opening yourself perfectly to repentence and forgiveness (tho that's probably harder, anyway :-)
But I think the DON'Ts, the precepts and commandments, usually work really differently in the two religions. In Buddhism they're basically just advice about how to how to live a life that's calm enough so that you can get down to the business of removing the confusions that obscure your Buddha-nature. But in Christianity following the commandments is itself a spiritual practice -- regardless of the outcome of following them or breaking them. By trying to follow them you discover the ways in which you resist the will of God. In a way, in Christianity, it doesn't really matter what the commandments are: they could be something like "don't climb trees" or "always wear gloves" and they'd work just as well. They'd still make reference-points you could use to identify when you wanted your own will, rather than God's will, to triumph.
Which is why it's so important for many Christians that the rules be simply rules, given by God once and for all. If they were just advice, as they are in Buddhism, they'd be useless for that kind of practice in submission to God's will.
When it comes to judging others, though -- well, that's when the Church and political power start warping the teachings of Jesus. Jesus didn't think you should spend your time on other people's transgressions -- he thought everyone had enough of their own to absorb their full attention :-) Trying to impose obedience to commandments on *other* people was something Jesus obviously had no interest in at all -- but churches and states have plenty of interest in it!
I don't know -- did I help at all with all that?