We are to help Buddhists be good Buddhists, to help Jews be good Jews, to help Muslims be good Muslims.
What did Our Lord say?
"Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost. Teaching them to observe all things whatsoever I have commanded you..."
Matthew 28:19-20
Mother Teresa was responsible for converting many to the Faith. It's just that she understood that the best way to convert someone is by the example of life, not disputation. Having been on the receiving end of "missionary outreach" by fundamentalists (who think I'm going to Hell because I'm a Catholic), I think that attempts to convert based on argument and disputation are often counter-productive today.