I would encourage my friends to come to our youth group.  The leaders are understanding; they've been through what we are going through now.  They are attentive and listen to us, and think about what they would do if they were in our situation.  They care for us all.  The topics we discuss relate to daily stuff.  The Bible study is tied into daily events in a teen's life and what teens go through.  The leaders cause me to think about what they say.  They really challenge me and have helped me grow spiritually through their strong encouragement.  It's a process; it takes time, but I see personal improvement in some areas.  They encourage us to read the Bible more and be willing to discuss with our non-Christian friends, both in and out of school, what we believe.  Sometimes I do that by just bringing up a topic like, "What are you doing this weekend?"  At school, we have a club called, Finding Adam; it's a Christian Bible study.  I co-lead that and encourage  the kids who come to think through their beliefs in light of the Christian faith.  One time a group of us were talking about religion and there was someone who was an atheist.  I did answer his questions and made comments to what he said, but since he argued with everything I had to say, eventually I just dropped it.  I didn't feel threatened.  Open discussion is a way to find out how others believe.