It's rude to push your religious beliefs on others.
John, who is a passionate atheist, is at dinner with a large group of his friends.
John wants to make conversation.
John has an open discussion with his friends about the meaning of faith and it's purpose in people's lives.
John goes on and on about how religious people are nutjobs and atheists are much smarter than them.
John's friends appreciate the interesting conversation topic, and they all have a good time.
John's friends find his line of conversation insulting and bigoted.