This is a hard thing that you must be going through. At 9 yrs old children start to make there own decisions about what they believe in and what they dont. Ultimatly baptism is your sons decision. If he is feeling pressured to do it that is wrong. Maybe for him he is comforted by this other religion and he likes it. I personally and a christian, and i would find it hard if i were in your shoes. I raise my child in what i beleive but in the end the decision is for her to make and i cant stop her from she beleives in. I am not sure on the rights of religion.
It is your son's decision. Talk to him, see if he really wants to do it or not. If not, then he doesn't have to. Religious issues are included in the parenting plan. They are in mine. If your son doesn't want to even go with them to church, he doesn't have to. Although parents want children to be the same religion they are, sometimes it doesn't work out that way, but you don't want your son to feel like he is being forced. Who has custody? Does he even have to attend church with his dad, if he doesn't want to? I think that if your son didn't want to be baptized in your ex's wife's religion, then he has that choice. It will be hard for him to stand up and say that, but he has every human right. Same goes with your religion. Just help him make the right decision for HIM, and make sure that he is going to be okay when dealing with disappointing you, his dad, or someone else. That is all we can do for our children. Even if we don't agree, we are responsible for giving them the tools to make decisions and stick by them.
Society has made it seem as if certian people just will never get along or ever have a good relationship. However sometimes it's true and sometimes it's not. Like supposably Mother-in-law and daughter-in-law or stepmom and stepchild. Than when there is a real problem and they don't get along people say it's all in their heads. I believe that this women is a constant harrassment to you! I also am outraged that she has the nerve to try to do this behind your back! As far as I am concered she maybe your child's stepmom but not by his choice or yours so therefore she shouldn't have a say so in changing something that is between you and your ex and your child. I could see if the little boy was acting up at his dad's house for no reason and being rude towards her and she was instigating the problem, than he should be disciplined and she could probably step in but not with something like this! Good luck!
I agree with the above poster.........as far as religion goes, a step parent needs to butt out. You and your ex had him baptized as an infant. Evidentally at that time, your ex was ok with the religion he was baptized into. So, obviously this is the stepmom doing this, and I too would put a stop to it.