I wanted to write you a message. I have never been a parent of a teen so I will not even begin to understand what you are going through. However, I have been a teen recently and I am a parent so I wanted to share something with you that I have observed. If you provide a godly example, if you lead your kids in what you believe is right, then they will almost always come back to that as an adult.
Being a teenager is all about pushing the boundaries and figuring out who you are and what you believe for yourself. It is about trying to pull away and establish yourself as an independent entity. Some behavior that is the opposite from what your parents believe is to be expected. It is them trying to figure out if everything you have said for the last several years is right.
I am not saying this to you because I think you are doing something wrong, or because I think I can do it better. I am saying this so that you can be encouraged. Your child is not behaving this way because he is losing his way, or he may be throwing away the values you taught him, or even because he doesn't like you. He is just trying to figure out who he is.
Someone wise once told me that you work really hard to instill the values you want in your child before they turn 12 or 13. After that, they take that and use it as a foundation to explore and figure the rest out on their own. I say, if you did it right, they will always come back to that spot to build the rest of their lives because they know the foundation you laid is strong and solid. Other children may seek to build a life away from their roots because they know the foundation their parents gave them is shaky and unstable.
If you are showing him what it means to lead a Godly lifestyle, then regardless of what happens in the next five to eight years, he will grow out of it, be a better person for it, and recognize that you are the ones that got him there. I have seen it happen time and time again.