I offer it as a resource because he is quite accurate in his description of what Christians agree upon, and what the term "Christian" has meant from the very beginning of Christianity.
“His point of view is that of an academic, and as such is an excellent starting point for academics. It is a primer, nothing more.”
It’s an awful primer for academics, who would be much better served reading, for instance, St. Augustine who embraced Christianity precisely because it made no ridiculous claims at being logically provable. I’ve read about five books now by C.S. Lewis, with people continually assuring me that I’ve thus far read the wrong ones and just need to read a different one to understand his brilliance. I’ve given up.
As for the point about what Christians agree on, I’d suggest that people read the various creeds that were adopted long ago — especially the Apostle’s and Nicene Creeds — rather than suffer through the embarrassing drivel of C.S. Lewis.