DEAR HIGHEST DRUNK DRIVING RATE IN THE COUNTRY:
Can a gay person raise a straight kid? Can a Scientologist eat bacon?
Do you listen to yourself talk?
I know stupidity hits everyone in some way, but you can't claim intellectual superiority anymore. You've done it. You've made atheists dumb. All atheists are now dumber thanks to that question.
Now, I know at some point a thought will rattle in your head regarding the religious upbringing of the child. So this will be easy: Just mumble the words in church, then forget all about the God bit. It's Harry Potter fandom to you, so what do you care? I hate Harry Potter but I still let my kids watch the movies and we have plans to read the (terrible) books to them as they get older.
And that's kind of the fucking point! You don't have to push YOUR non existent religious beliefs on a kid while encouraging their spiritual growth. What you CAN do while the cognitive function increases in the kids noggin, is introduce them to different religious ideas and allow them to come to their own conclusions. As long as you leave out your own "Christians are dum dums and me am smart" and don't try to edit the facts to lead to your way of thinking, you should be fine. Introduce weak and strong anthropic principle. Treat it as though you are leading them to be critical thinkers.
But before all this, talk to the parents instead of asking an advice column. They'll tell you what they want for their kid and you can turn them down if you want. No advice column can give you this permission.