Did they send her to a Christian school because they wanted her to be a Christian?
Wouldn't they attend a church first?
I had to deal with this problem when I was chairman of a Christian school.
Most of these schools have an enrollment contract which states something like “We recognize that Little Sally will be taught the Christian religion, and we contract not to deny or disparage its essential tenets at home”.
Raising a child in a home with unmarried parents or with two persons of the same sex engaging in sexual relations while proclaiming in public that it is normal or blessed by God is considered by most Christian school governing bodies as “denying or disparaging” the Christian religion.
To be fair, most of these schools are more likely to accept a child of heterosexual fornicators that they are a child of a same-sex couple, but then there is that whole abomination thingy to deal with.
Most of the time, when a homosexual or lesbian couple brings their child to enroll at a school which teaches that the couple is an abomination, they are using the child to attack the fundamentals of the school, which fundamentals they despise.
It’s not “punishing the child” to refuse a contract signed in bad faith.