I had a bit of a rebellious streak in my youth, and I am sure that there were times when I adopted a minority position simply to rebel against authority. This was probably also a contributing factor to how outspoken I was about my atheism during my college years. But while it may have contributed to my assertive behavior at the time, something else was far more important in shaping my worldview: skepticism and my willingness to ask "why?"
I recently mentioned to a couple of friends that I probably won't watch the Super Bowl this weekend. They acted shocked and asked what was wrong with me. I responded that I truly didn't care who would win and thought that I could find better uses of my time. Their response was telling. "But it's the Super Bowl!" The fact that this is not a compelling argument for me is not due to my wanting to rebel against cultural norms; it is due to my asking myself why I should do something I don't expect to enjoy just because someone else thinks I am supposed to do so.
Most of the interactions I have with others around Christianity seem to fall into a similar pattern. They blindly assume I share their Christian beliefs, I explain that I'm not a Christian because I do not have valid reasons for believing what they do, and I face shock, disbelief, and even condemnation. Again, it isn't like I decided not to be a Christian because I want to be an outsider for the sake of doing so or because I'm trying to rebel against something. I merely find myself asking why I would base my worldview on ancient myths without evidence.
I've lost count of the number of times I've been accused of failing to go along with cultural norms due to a desire to rebel or flout authority. But ultimately, the reason I don't go along is much simpler. I reject blind faith and keep asking why.