How do you deal with a stepparent with a totally different religious view?

They are your children, you put your foot down.
I would never take it upon myself to force something on my stepsons that my husband, or the boys, didn’t want. It isn’t my place. It isn’t your husband’s place, either.
Sometimes being a stepparent can feel very much just like regular parenting. You grow to love the children as your own, you take care of them, provide for them – but there are fine nuances like this that will never go away. He needs to learn that.

Unacceptable. As much as a blended family is a family nonetheless, you may have to fall back on the argument that these are your kids, and when it comes to some big ticket items, you’re going to have the final say.

I would ask, however, whether you object because you want to raise them according to your religion. I understand if you don’t agree with me on the following, but I feel like that’s just as inappropriate as relating to the children (note – he’s in a worse position because he is imposing it on the children and you).

So…is it a religious conflict situation, or a situation where you’re not raising them a particular way, and he is attempting to force his position in….

If the kids truly don’t want anything to do with his religion, he should accept that.
If the kids were curious and wanted to know more, I’d hope that you’d let them listen to what he has to say and make up their minds for themselves.

What religion is it, out of curiosity?

The real question is why would you marry someone with a strong belief that is completely different than your own.

Did you not bother to discuss this with him?

What if you two have childern?
Is he supposed to abandon his beliefs or convert?

I’m with @Seelix and @Dog- having strong religious views of any kind is one thing and love works with that but not to uncomfortably instill them on kids, birth kids or otherwise, I don’t believe in it.