For an atheist, you're really fucking stupid.
I grew up in an Italian family and I was designated Roman Catholic without my consent. My grandparents drilled it into my life, My parents forced me to do my communion and confirmation, I was baptized at 2, and what happened to me?
I turned 8 and realized it was all stupid and made no sense. I realize that social engineering and dynamics are important and that pretending is a useful thing. I pretended to accept my faith and in turn, I had many friends, and my family loved me. I realize not everyone is like me, and i'm willing to compromise and bend a little for the world so I can get what I want/need.
Here's what you need to do: Go to your wife, say you saw the light, you believe in God, religion makes sense, you're changed. Your parents will accept you. Your girlfriend will take you back, your girlfriends family will love you, and your daughter gets to have a nice party and some water put on your head.
If your daughter has an IQ of more than 50, she too will realize just how non-sensical it is, and when you and her come to realize that you're alike, you can attend stupid church sermons and wink at each other as if it's your little inside joke, and that's the special bond you'll create with your daughter for the rest of her life and it will nurture her and not give her crazy trust issues. You and her will have a sociological bond of you two, against the world, but more important, she will have a parent that is on her side and gets her.
If she turns out to love religion, well keep it to yourself and realize your daughter isn't going to grow up to cure cancer or discover the next big breakthrough in new energy, but hey, we can't all be winners.
TL

R: LIE. Lie about fucking everything, save your daughter's life, and I'm a big fucking prick, but who cares.