I raised my 2 sons as a loving, atheistic parent. I agreed that they could go to the Catholic Church when they were with their Dad, but made it clear to them that they should use it as background knowledge and make their own decisions according to what they personally believed.
They would hear my rants on occasion, when a creationist program would be on TV, so they were very aware of my thoughts on the matter. Because I was raised in a religious family, I knew the damage indoctrinated religion could do and I didn't want to force such a thing on my sons. We discussed life, death, and everything in between, quite freely. I was proud that my sons, when grown, did not blindly follow the rules of a religion that had no evidence and that was based on fear and guilt. I taught them to question ANY authority (to my chagrin, occasionally!) and to use their minds and reasoning to make decisions.