Papa John -- PIZZA TRAITOR!!!

PJ's finally responded, and says ... he did not fork it up.

Papa John is like Benedict Arnold slathered in marinara sauce!

We got PJ -- aka John Schnatter -- chowing down on the competition at the Sundance Film Festival in Park City, Utah.

A far cry from the chain, the pie was served up at the uber-fancy St. Regis Hotel.

But his real transgression is the method ... HE ATE IT WITH A FORK!