I would support my son if he became religious, but I would question him on it and debate his views. Religion is a part of school life in the UK, I wish it wasnt. We already teach various religious beliefs in school classes but they sing Christian hymns and take the children to church and essentially teach them, in their youngest years in school, that Christianity is the correct religion.
My son came home one day talking about a man who was raised from the dead and healed people. He said he saw it in a video in school and was of the impression it was completely true, because why would school lie to him?!
I told him that I didnt believe the things he was shown, I didnt believe that person was brought back from the dead, nor did I believe he cured people of blindness etc. In fact, I told him I didnt believe that person even existed and was a fabrication. I can feel many people getting upset about that :)
But I was accepting, I didnt tell him that is WAS wrong, that he shouldnt believe it, I simply told him what I believe. He is free to make his choices and I will support him in whatever he chooses in life (apart from deciding to become a mass murderer, that... Im not so supportive of)