Why did Ted kaczynski do what he did?

Answer 1

Answer 1: Atheism. Judging by the fact that he was Polish-American he was probably christened as a Roman Catholic.

Answer 2: Actually Kaczynski was a Polish-American in Chicago, specifically, and so if we're going to speculate, I'd speculate that he was probably christened as PolishCatholic, rather than Roman Catholic. Polish Catholicism is its own official thing, intentionally separate and apart from Roman Catholicism, with some quite intentional departures therefrom. It is nevertheless acknowledged by the Roman Catholic Church, and its apostolic succession is viewed as valid (even if irregular) thereby.

Chicago has the largest population of Polish Catholics outside of Warsaw or Krakow, so it's far more likely that if Kaczynsky, being a Polish-American, was christened a Catholic of any kind in a place like Chicago, then it was most likely Polish Catholic. I could be wrong, but I'm just sayin'.

As for Atheism, most secular humanists would have a huge problem with anyone categorizing that as a religion. So, then, if Kaczynski was and/or is an Atheist, then that means he had/has no religion, not that his religion was/is Atheism. And, in fact, even an analysis based, simply, on the definition of the word "atheist" or "atheism" confirms this, prima facie.

For whatever it's worth, though Kaczynski's brother, David, was working as the assistant director of a homeless shelter in Albany, NY when he figured out that the Unibomber was his brother, and went to the FBI about it, it was, nevertheless, a secular (non-religious) shelter. And David, today, is a Buddhist. So if any form of Catholicism was any part of their family's heritage, it certainly didn't stick with the Kaczynski brothers. I sent David a private email (over a month ago, at this writing in August of 2012) asking what is the story regarding his brother's faith, and he has not replied.