Telling a person that their beliefs are wrong is not a popular thing to do as they can get upset and often react when they find that what they've been taught to believe is wrong. Even Paul had to deal with this when he asked the Galatians this question: "Am I therefore become your enemy, because I tell you the truth?" (Gal. 4:16). Although bearing truth to your Mormon friends isn't always easy, it can be very rewarding when you share truth in a loving way and the person responds in leaving the lies of Joseph Smith for the truth of Christ.