It's not of the Lord to gossip or condemn other Christians. The Bible sets forth clear instructions on how we are to deal with a Christian who is not preaching/teaching the Word. When people attack other Christians and have not follow those instructions, then they ought not to be condemning others. The Bible tells us to watch the words of our mouth and to guard our tongues, because they can be deadly weapons, and can literally ruin people.
If the Bible tells us to "watch the words of our mouth and to guard our tongues", how much more so should we watch what we post on these forums, since we have all the chances we need to preview what we write and give our written words due consideration.
So--if uncharity comes from our written words, which we have a chance to review, then we are more than ever responsible for them