At Touchstone’s website, N.T. Wright offers a retrospective and appreciation of C.S. Lewis' Mere Christianity, one of the most Catholic books by a non-Catholic, on the sixtieth anniversary of its publication. Further discussion here.
This thin volume has brought countless souls to Christ, many of whom eventually became Catholic. If you've never read it, or even if you have, it's well worth a read. It will strengthen your faith and sharpen your skills as a "fisher of men".