I will reply not with my own view, but of the person who is most likely the author if this tract: Jack Chick. "Catholics are not Christians."

Absurd, you say? Of course, and I agree that it's absurd.

In the US there are two broad categories of people who would disagree.

1. Old school bigots, many of whom came from immigrant families and wanted to align with the ruling class in America: WASPs. These were generally families who came from northwestern Europe and Scandinavia. (This describes the oldest members of my own family, who are still scandalized that my uncle married a woman from an Italian family in the 1960s).
2. Fundamentalist Protestants. There are a thousand different flavors, so it's hard to give them a single name. They agree that the bible is the literal word of God and that Catholicism is fundamentally flawed - as is any religion that stresses the need to "do unto others" in any significant fashion. "The only way to heaven is through me," said Jesus. In other words, if you're a serial killer but you truly believe in Jesus Christ and have pledged your soul to him - well, Jesus must have a good reason for all that serial killing you did. (This describes my in-laws, so yes - my entire family is fucked up).

The serial killing thing is a bit of an exaggeration, but honestly - these people are almost shockingly mean to each other.

https://en.wikipedia.org/wiki/Chick_tract