Both Galileo and Newton were Christians. Galileo never renounced his faith.
Both Galileo and Newton may have actually believed but, for self preservation, they would have to claim to be 'true believers' even if they weren't. Sorta like if there is an atheist living in Mecca today then they would have to claim to be 'true believers' or find themselves being stoned to death.
I'd have yo look it up, Newton was a bleiver but had some off beat beiefs on the Trinity that could have gotten him into trouble. I think I think Newton used god of the gaps at times.
I read a bio of Galileo that came out of MIT. He was a believer and initially the pope was his ally, but faced ptessure. Initialy it was not theology per se, but push back from academics who made a living teaching the orthodoxy. I think he ended up confined to his house. His faith may have saved him from execution.
The transcript of his religious trial used to be online.