"She said 'It's not now or never, wait ten years we'll be together'"
Aside from being raised in a religion that doesn't accept you or that you don't want to follow, the strongest feeling of being an outsider comes from being a third wheel in any type of relationship, romantic or otherwise. This feeling of being an outcast from any type of community is a driving force for people to go out and discover the "truth".
"Taste the blood, broken dreams, Lonely times indeed"
While being in a religion you don't believe in has a profoundly negative effect on people, religion as a concept is a good thing. Without the feeling of belonging to something or being accepted by someone humans feel broken or like they're missing something, religion fills the role of being the one thing that can make us feel complete. Although sometimes big religions take advantage of that and use it to exploit their followers, which is not good.
"Stay in the shadows, cheer at the gallows, this is a round up"
What is considered normal and even what is considered abnormal varies drastically from person to person. What people experience in their lives and how they react to those experiences makes each person unique and completely different from anyone else, so its a foolish endeavor to believe that there's going to be only one true way to live your life. What one person find appalling and even evil can represent something completely different to someone else.