Do you have to join in the Christian or religious activities to stay there?

I've been to the camp, there is grace at meals but it is by no means required. There is also worship service at times, but there's always something else to do. (I know this is late but it's just a definite answer)

There is grace at meals, and if you go to camp for 2 weeks then you can choose if you want to go to the worship service on Sundays. But, it's optional.

I believe that the owners are Christian, but there are no religious activities within the camp. I think you are thinking of another Sandy Hill Camp that is religious.