Question About Avodah Zarah and Christianity

I’m not Jewish but am curious and researching certain topics of interest, one of which is the rabbinical view of Christianity. I’ve heard a few mixed things on the subject. My primary interest is the Jewish view of Catholicism versus other Christian denominations.

I once heard a Rabbi say “There are only two real religions, Judaism and Catholicism.” I’ve also seen Jews refer to Christianity as “Christianity (Catholicism).”

According to Talmudic teaching, Catholicism is considered avodah zarah. Many Protestants, especially those against iconography, also consider Catholicism to be idolatrous. What do Jews think of Protestant sects that are anti-Catholic?

Also, according to Jewish teaching, why is Catholicism considered the epitome of Christianity?