Sounds like Bertrand Russell or...Al Franken.
Now if you replaced "Christianity" with "Christendom", that'd be another matter entirely.
Back at university in the 70's, I had an atheistic philosophy prof who was a "fan" of CSL---so much so he wrote a book in order to pummel a straw man he dubbed C.S. Lewis.
So be very wary of secular "fans" who drop CSL's name.