Can a foster agency legally require foster parents to teach children religious beliefs and practices?

We are in Georgia, and looked into a foster agency that was not explicitly Christian on their website, aside from indicating that they supported the "spiritual" wellness of the child as well as the physical and emotional. My husband and I are not religious, but we were fine with supporting any spiritual practices that the child's birth family might encourage.

We arrive at the agency to find Christian verses everywhere. The staff was startled and confused that we aren't Christians. They didn't say it explicitly, but it was clear they were concerned that we wouldn't be exposing the children specifically to Christian material (unless the birth parents requested it).

They are clearly resistant to accepting us as foster parents for this reason alone, even though they admit they have no concerns in any other area of our application process. They state that regardless of whether a foster child's birth parents are religious, their particular agency would require the foster parents to expose the foster child to religious practices, with a heavy preference on Christianity. They were very careful in their wording.

My question is...is it even legal to require foster parents to expose children to religious practices? This might be a private foster agency, but they are accepting kids from the state.