My mom was Jewish and my dad was Christian and we were raised Christian. My mother decided to go back to Judaism in her 30s and was basically told "too bad, so sad, you didn't practice as an adult and didn't raise your children as Jews (and didn't have the adoption ceremony as a baby), you can't get back into it." She's an atheist now.
My cousin married a muslim and converted to Islam as is raising his children as muslims.
The people who are saying since you are both theists you should raise your kids as non-theists is a bit strange. It's not an unacceptable option but it's also not a stronger choice than many others.
The argument that "well atheism is right and christians and muslims are wrong" doesn't sound any more clued in than some theists that argue they are "right because they are right"