One problem I have with people using religion to try to better themselves in prison is that it doesn’t automatically result in change. In fact, often times, the Christian message is (or becomes, rightly or wrongly): You’re just great the way you are. God loves you. Now just worship and say some magic words, and everything will magically work out in your life.
But it doesn’t work like that. Change is really hard, and it often takes years and hard work and LOTS of self-criticism. That’s definitely what it took for me.