I personally consider myself spiritual rather than religious and the way that affects my decisions about sex is that I probably won't wait until I'm married, but until I find that special someone. Spiritual means they believe in a higher power but they are not very involved in his worship. Religious means that you worship a higher power on a regular basis. It doesn't matter if you are spiritual or religious. Some religions say you can't have sex until you're married, but some people don't even care.
Teens have a choice to do what they want with their body and lives.
You just need to protect yourself. I believe in God, but I'm not religious or spiritual. I think sometimes teenagers doubt their religion. As far as the way this affects decisions about sex, I would say it makes it easier for them to disobey and keeps them from feeling guilty. I myself am very religious and realize that there truly is not a difference between religion and spirituality.