My uncle’s philosophy for raising a child (cleaned up):
“Teach them what you know, let them figure out the rest.”
The problem comes when people think that they know things that they in fact do not know. I plan on teaching my child (or a child that I raise) how to be autonomous and appreciate life. I think that those two are the most important things for a well-lived life, with rationality and ethicality coming a close second.
And since I know not any metaphysics or the soundness of any religious teaching, I will avoid teaching my child those things. I might mention what I believe, but I’ll try to avoid prejudicing the kid.
It’s the only way to go about it, really.