Frank Tipler is a crackpot. At one point in his life, he did very good technical work in general relativity; he was the first to prove theorems that closed timelike curves could not be constructed in local regions of spacetime without either violating the weak energy condition or creating a singularity. But alas, since then he has pretty much gone off the deep end, and more recently has become known for arguments for Christianity based on fundamental physics. If you closely at those arguments (h/t wolfgang), you find things like this: