I agree with you in that it is not right to judge someone based on his current belief system. Perhaps they've never had a sufficient opportunity to hear the truth. However, Jesus and his apostles clearly commanded Christians to evangelize. For a follower of Christ it is right to do what Jesus did, and He did point out to people around him the errors of their ways. He graciously spoke in parables but he was not silent. He silently accepted his cross; there's a difference.