Good for you Irishmommy!! My dd (now 8yo & in 3rd grade) decided in K or 1st grade that she believed in heaven and angels, but not God. Dh and I are not sure what we believe about God, but believe that we can't MAKE someone believe anything they don't want to believe (spiritually). We are a Unitarian Universalist family, and so her beliefs are hers, and ours are ours.
Really, the biggest problem occurred in 1st grade when the Catholic kids were going through 1st Communion ( I think) and at Easter time..... they said really mean things to her----she'd die the next day if she didn't believe in God; "Don't sit next to her(dd) or you'll go to hell", etc.....For weeks this went on and I didn't know. The teacher didn't know and dd didn't say anything to me. Finally they called me to school on another matter and I sat down with dd and we solved the initial problem, but she was still sad. Then this tormenting came out!!! I felt so angry that these little kids could be so mean!! The next day the teacher had a presentation on the separation of church and state---we talk about school in school and God/Religion at home or away from school. The subject didn't come up again until the next year, and the next teacher dealt with it in an acceptable manner also.
I'm only mentioning this part to say that even in a public school, there was the issue of problems with the other kids. Maybe since they're older yours might not have this issue--hopefully the older kids are more tolerant of their differences--but be prepared for that discussion too.
Your dd sounds like my dd in that she's a strong person who knows her beliefs and is interested in exploration.....G'luck!!!

