Is this wrong for me as a Christian?

My cousins are really devout. I'm a Christian as well, but they've taken it to the really judgemental level. They always talk about people who are sinners and how they are going to hell. They even say it in front of some people like they're trying to be subtle. They always get mad at me because I always argue to "live and let live". I believe that if someone wants to live a certain way, they should have that right. Is this wrong to believe as a Christian? I know the Lord wants us to preach the gospel and lead as many people to the light as possible. I just don't feel right trying to tell someone how to live THEIR life. I wouldn't want someone to do that to me. My cousins, and their parents, seem to think I'm misled.