When you interact with them, try to be respectful, listen, and keep a good tone of voice, especially when they are being frustrating. This will help them see you as growing into an adult and showing maturity.
Ask what you can do to show you're trustworthy and earn more freedom.
Tell him you would like to make a plan in advance to go somewhere. It's a reasonable request and there is no good reason that can't be done. If his parents are the problem, tell your parents you'd both like to make plans as they suggested but his parents are refusing to make plans beyond today (or whatever they said) and would they please discuss it with them. If they say no ask what they think it's best you do in the situation.
Tell them you'd like more friends your age and ask if you may take a class, or go to a camp in the summer, or get a job, or volunteer work.
Consider talking to someone in your church about your concerns about Christianity.
I was a teen with a very restrictive mom and I've raised teens.