They are little (around 3X5) booklets passed out by certain stripes of Christians. Each one addresses a particular variety of sinner in a comic book format and shows how Jesus (well, Jack Chick's take on Jesus) can save said sinner from eternal damnation.
Jack wasn't shy about going after other religions either, he had 20 tracts on how awful and sinful Catholicism was. He didn't like Mormons, Jehovah's Witnesses or Muslims either.
He also addressed homosexuality (hated it), alcoholism, and evolution too.
The granting of a pardon is an imputation of guilt, and the acceptance a confession of it.