Does the Catholic Church think Protestants belong to a different religion?
No. The Catholic Church does not think Protestants are another religion. The Catholic Church uses the phrase “separated brethren” when referring to Protestants. In fact, the Catholic Church teaches that there is only
one Church and that Protestants, while not in full communion, are part of that one Church.
For example, the Catholic Church recognizes as valid the baptism in most Protestant denominations. The Church teaches that when one is baptized, they become part of the catholic (note the lower case) Church. In this case “catholic” means "universal.
Last summer (July?), the Vatican released a document clarifying this very subject. There were some threads here about it because the mainstream media distorted it and made it sound very anti-Protestant, which it was not. Here is a copy of the
official translation which came out in August. Here is one of the
threads that discussed the distorted news stories.
(On a side note, I did not see your post which preceded mine before I posted. I think that is because I think I started writing mine before you wrote yours, but posted it after you. Or is it the other way around? :whacky: )