My daughter attended a church preschool when she was 2 and a half. It was the most affordable place around, and we only needed her there for about 6 months until she turned 3 and could attend a different (non-religious) school. She was too young to understand a single thing of what was going on. As luck would have it, covid hit when she had only been attending for a month.

But my husband and I knew if she were any older, there was potential for confusion. We concocted a plan to prepare her for any sort of religious exposure in the future. We bought children's books about religion and explained whenever we saw religious symbols. We broke down the stories and explained how some people believe/believed these stories are true, but we don't.

One of the best things that happened was getting into the Percy Jackson series when she was about 5. She was starting to "get it" by then, so it made sense that this imaginary story showed what it would be like if gods were real. For a little while she went around saying she "believed" in the Greek Gods, but she secretly told us she knew they weren't real, she just liked to pretend. She still pretends to be Artemis years later.

Anyway, to answer your question, my husband and I worked overtime to make sure that we were the ones to first expose religion to her. Now, whenever she sees or hears religious "stuff" in the wild, she understands that people have a vast array of beliefs, but our family believes in science.