Leave the stuff where it is.
It is your home. They may be your husband’s parents, but they are still guests and they can either respect you in your home or leave.
We have some Catholic things (crucifix, rosaries, books) and we have some people who are generally not too thrilled about religion, but no one has ever been rude enough to attack it in our house.
My MIL wasn’t happy when my husband decided to get baptised.
She was very negative about it and negative about us celebrating it and her coming to church to see it. On the day of the baptism she said that in her opinion he shouldn’t do it at all. His only response was that no one asked for her opinion.
I’ve seen him disagree with his parents, but that was the only time I’ve heard him talk to her in such a strict tone. Not yelling, not offensive, but a very clear matter-of-fact tone, adult to adult. And that was also the last time I’ve heard her such a comment from her.
Our wedding was also in a church, of course, and she was happy about the marriage, we like each other very much, but I don’t know if she had a negative opinion about the religious aspect of the wedding itself. She never said a word.
The big Bible, the fact that we go to church in their neighbourhood if we are there on Sunday… Not a single comment.
I have non-Catholic friends and I am okay discussing many things concerning religion or lack thereof. But conversation and discussion is one thing, attacking it just for the sake of spewing venom is something completely different and is not tolerated. From anyone.

What was his reaction to this?