Does God give us the right to judge each other?

Why are most Christians you meet so judgmental? I smoke cigarettes, which is a terrible habit. I am fully aware of how bad it is for me. Yesterday I was smoking a cigarette outside work and this couple walked by and gave me the most hateful look I think I have ever received. It honestly really hurt my feelings. The church I used to go to has told many people I used to be good friends with there not to come near me because I smoke cigarettes and they hear rumors that I do coke(I have no idea who thinks that-I don't). So all my old friends who I loved so much now spread these terrible rumors about me and judge me on them. I believe it is because I'm not going to church anymore. This really hurts me-I actually got engaged and there was this face book message going around to all of them to not get too excited about my engagement because they hear he's a druggie and convincing me to do terrible things. Anyways, I just wanted to ask why almost all of the Christians I have encountered are so judgmental?