Christmas_Freak, as Bobbi said you have to make the decision to trust and believe in the Lord despite what others may say at times. I'm not sure if you are speaking of Christmas movies or something like Angels and Demons which just came out, but no matter what it's uip to you to decide if seeing a certain movie is a "sin".
Many people can go overboard with what they believe is "against" God. The only thing we can truly base it on is His perfect Word. Don't let anyone make you disbelieve what it is in your heart that you know is true and perfect. God is the one who has the last "say" and because we were all born sinners we must repent through the grace and love of our Lord Jesus Christ."This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference, for all have sinned and fallen short of the glory of God, and are justified freely by his grace through the redemption that came by Christ Jesus." ~Romans 3:22-24
Hang in there and let us know if we can help! I hope we've helped you out in some way already...