woah woah woah. caygirl please listen to what i have to say. this advice is all good, but if they really are non believers you've got to be careful about quoting scripture. we want to christinaity to be a personal, meaningful thing, not a few lines of jargon that we spout off. so my advice is this: be very careful about who you hang about, and when you're with them if they do something outrageous you may have to tell them to stop and get out of there. otherwise just do your best with God's help to resist any evil they do. BE a friend, and don't nag them about religion. A lot of kids our age (I'm 17, and I understand what you mean about being mature. I feel like my mind is at least 3 years older than the rest of me and my friends in some areas) don't want to here religious stuff blasted at them. I advise that instead of quoting scripture if the opportunity arises respond or speak casaully---aka say the scripture, but don't quote it. get the message across correctly but not by quoting it. rather, give them the meanign, give them the spice and truth of scripture without directly quoting it. I think you'll find that they'll (at least, i hope for more) not bash you about jsut saying something good rather than popping off a bible verse. try that, but dont' get pushy. we want them to find christ, not get shoved into a closet wtih him.
God bless you, fight the good fight, teen years are hard, i know cuz i'm there and there's so much evil out there it's pathetic, especially with sex stuff. you and God can do it. Together you can accomplish anything.