I have zero issue with this, “invited” means just that, and it’s fine to say no.
Our last three children attended a very multi-cultural primary school, where I was a school governor the entire time they were there.
Each Easter and Christmas, Christian celebrations took place, each parent was written to and asked to come into the school and watch and each parent was given the opportunity to withdraw their child from any nativities or other Christian activities. None did withdraw their children. I absolutely loved seeing all their different faiths/races/colours all taking part in a conventional nativity.
During other faiths festivals/holy days parents were invited into assembly to talk about what and how these celebrations were held.
Often these parents would cook traditional food and bring it in for children to try.
Our children grew up alongside children whose first language was not English, who didn’t share our culture or faiths, but who all became friends.
Our youngest DD had a friend who was Polish and another whose entire family fled from Zimbabwe, and she ate in their homes on several occasions.
Understanding other faiths and cultures can engender tolerance and widen knowledge.
I was fortunate, whilst in the Civil Service, to work alongside amazing Muslim men and women, if asked, they were more than happy to explain their culture and faith. A couple were married to white British people, all of them were kind and lovely people.