I may have missed it, but I didn't see where Mom had a problem with Dad's beliefs on baptism. I saw where daughter feels she was baptized before she was ready and to that I think Dad should have daughter speak to their pastor or whatever his title is and explain how she's feeling now since that was between them in the first place (assuming he had to approve she was ready in the first place).
I'm not saying it's about Baptism exclusively. I'm saying Mom obviously does not share all Dad's Religious views. And, apparently, neither does the child. So, if Dad & stepmom are saying she (or friends/family, whomEVER) are going to go to Hell if they don't do x,y, or z as in accordance with their faith...well, they're teaching her to discount/negate/look down/shun (or WHATEVER verb you like best)....and THAT is exactly what Bigotry is. Not to mention they may be scaring the sh*t out of the poor kid, who's obviously confused enough as it is right now...and who may fear she will be going to hell herself!
And, while I do not share the belief that hell is for the unbaptized, teaching that does not = bigotry. It's too easily disproved how much unconditional love and caring comes from people that have this belief to say ergo they are also a bigot. Remember that OP and those of her faith aren't condemning anyone in the first place.