Spoilers ahead for The Punisher Season 2. If you're going to be an enemy of The Punisher, you're going to need to be pretty darn brutal. Frank Castle isn't someone whose sense of morality can be manipulated as easily as upright citizen Luke Cage or the walking pillar of Catholic guilt that is Matt Murdock. Unsurprisingly, John Pilgrim — who makes his debut in The Punisher Season 2 — is a worthy adversary to Frank Castle by upping the brutality with a healthy dose of misguided faith. He's a quintessential comic book villain, which makes it pretty surprising to learn that John Pilgrim is not in the Punisher comics, and is original to the television series.
When John Pilgrim first comes across Frank Castle, he has no quarrel with him. Unlike fellow Punisher foe Billy Russo, there is no personal vendetta between Pilgrim and Frank. Unfortunately, Frank Castle goes and puts himself between Pilgrim and Amy Bendix, a young runaway that John Pilgrim and a collection of goons are on the hunt for, and then Frank Castle very quickly becomes John Pilgrim's No. 1 enemy. While Pilgrim is exclusive to the show, a few key episodes manage to drop some hints about his past that allow the audience some insight into what makes this supposedly holy man tick.
At the beginning of Episode 3, audiences are introduced to Pilgrim as he is attending a bustling ministry during a church service. The preacher takes some time to give thanks to two of the Church's wealthy benefactors, who pulls Pilgrim aside after the service to ask a favor. Pilgrim is in their debt, as it seems they've provided his ailing wife with a hard-to-access medical treatment that is keeping her alive. In return, he is asked to attend to a "serious matter," to which Pilgrim replies that he welcomes "any opportunity to prove [his] faith."
Pilgrim is then seen tracking, and eventually trying to capture, Frank and Amy, but those unfamiliar with bigoted iconography may have missed a key detail into Pilgrim's past. On his body, faded tattoos beneath what appears to be an attempt to cover them up show that John Pilgrim, at one point, proudly displayed an Iron Cross, a Skull, and the image of a Reichsadler on his body. These symbols are all associated with Nazi and Neo-Nazi iconography, and his history of violence suggests that while he may not as vocally interested in white supremacy as he was in the past, those beliefs still exist at his core.
However, in episode 12 when speaking with Curtis, Pilgrim explains that there was a time where he would've judged him "before even sitting down with [him] ... Just a glance, I would've seen you as unclean, a dishonest man. Less than human. It was a brutal life, I put that behind me." While Pilgrim may have put his Nazi days behind him, he is still very much not a great human being, what with the murder and the racist threats. Pilgrim's character is an exercise in challenging the idea that faith, in and of itself, is a virtue — especially when that faith calls for violence and bigotry.