When people act like that, the chances are they are either new in their faith or the Spirit of the Lord is truly not in them. There is only one who knows who will be saved in the end, and that is God. People who are Christians should strive to be the best example they can without judgment and condemnation.
I have written many articles on the advent of the church at large and their judgments on others because of their differences. Sexual, doctrinal, traditions, faith etc. Everyone believes that what they believe is correct, and we should all be sensitive to everyones right to believe what and the way they choose.