He is referencing (and possibly believing) an urban legend that General Pershing dealt with Islamic Terrorists in the early 20th century by executing a a series of them with bullets coated in pigs fat, then letting some go to tell the tale. Another retelling is that he buried them with pigs. Either way, the story goes that this would stop them going to heaven, and thus struck the remaining terrorists with such fear for their souls that it completely stopped all Islamic terrorism, instantly breaking all resistance.

It is neither theologically accurate (shot to death with pork products or an enemy burying you with pigs does not mean you are denied an afterlife) nor historically accurate (it never happened).

Do we consider "Snopes" to be an acceptable source for something like this?. It has a great write up in any case.

These is a lot of information here about US atrocities in the Philippines https://www.reddit.com/r/AskHistorians/comments/1wi3od/why_did_the_united_states_of_america_win_the/