In early 2021, Representative Byron Donalds, Republican of Florida, and his wife, Erika, took the stage at an event hosted by the Truth & Liberty Coalition, a group that pushes to inject Christianity into public schools and other institutions and whose leader has described homosexuality as Satan’s work.

The couple was warmly welcomed as allies in the cause. Mrs. Donalds was singled out for opening a charter school in Florida. As a state legislator, Mr. Donalds had created a school voucher…