My husband was really reluctant to do the whole Santa Claus thing. I think a big part of it was that he wanted the children to be aware that we were doing this for them, not some mystical being. I personally don't ever remember believing in Santa Claus, but I do remember being about 4 yo and reading a gift tag that said "from Santa" and realizing it was my mom's handwriting. When we were first married, before we had kids, we talked about how we weren't going to teach the kids about Santa, but he is everywhere, and starting around last year, when our oldest was 3, I found myself wanting to talk to him about Santa. I found a great blog post which summed up how I feel about the whole thing. For now, we emphasize the religious part of the holiday, and Santa is a part of it, but simply as someone who loves Christmas and the Christ child so much that he spends all year making presents for all the children of the world and then delivers them Christmas Eve to spread the joy.