If you wanna get rid of something, worst thing you can do is try to get rid of it. Romans tried to get rid of Christianity and were a lot less squeamish about slaughtering Christians than we would be. They failed. They actually helped ensure it took hold and got popular.
My suggestion is simply counter Christian points every time you encounter them. "God created the Earth in 6 days." - Counter with something like, "Really? So it took Him 6 days to create 1 planet orbiting 1 star. There are how many stars? Each likely with at least 1 planet. Doing the math...UH-oh looks like it woulda taken God over a qunitillion years to make all the planets in the known universe. Universe is only 13.5 billion years old. Explain this problem."
328 quintillion years rather, looked up my previous thread about it. It's here,
6 Days... US Message Board - Political Discussion Forum