My Freeper handle is from the CS Lewis space trilogy. That Hideous Strength is one of the most prescient books I have ever read. That said, there is a bunch of great Christian sci-fi besides that.
Gene Wolfe, RA Lafferty, the tragic Walter M. Miller all wrote and in Gene Wolfe’s case still write.
Freegards
Gene Wolfe is a Christian??
Oh, and for Fantasy -- Stephen Lawhead did a great series on the Arthurian legend...and a couple of quasi-historical novels on St. Patrick, and on Robin Hood.