Most Catholics have never studied the official teachings of the Church of Rome—at most they have only studied the Bible and think there is no conflict. I know that from first-hand experience—I was Roman Catholic for 44 years.
The Roman Catholic Church teaches "another gospel". These pages contain excerpts from the official Catechism of the Catholic Church and from high-level Catholic clergy, e.g. popes, to document how official Roman Catholic doctrine contradicts basic biblical doctrines regarding salvation.
POINTS TO CONSIDER
The following Catholic Catechism excerpts were downloaded from a website. I have expanded abbreviations of the names of Bible books, e.g., where the Catechism has "Rom." I have substituted "Romans". Any other text that is not in the original Catechism text is in black and marked in square brackets.
When reading the Catechism text, it is extremely important to notice something: the Catholic Church usually supports its doctrines by referring to Catholic Church pronouncements, edicts, etc., not by referring to the Bible. The Bible cites are usually "cf", meaning "confer". A "confer" reference means "this sort of deals with the same general subject." It does not mean "here is additional text that is directly on point."
One of the main areas of apologetics is comparative theology, to determine and substantiate (1) which teachings are true, (2) which are false, and (3) which can neither be proven nor disproven because the Bible does not provide sufficient information. When it came to false teachings, both Jesus and Paul had no qualms about saying straight out 'Your teachings are false, and here's why.', e.g., Jesus' refutation of the Saduccees' claim that there is no resurrection (Matthew 22:23), His refutation of the teaching of corban (Mark 7:11), and Paul's refutation of Nicholaitanism (the false teaching that sexual immorality has no effect on the soul/spirit because it occurs in the physical body, not the spirit).
We must not ignore false teachings in the interests of fake and self-contradictory "church unity." 2 Corinthians 6:14b-15a For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness?  What harmony is there between Christ and Belial? In Matthew 10:34 Jesus said "Do not suppose that I have come to bring peace to the earth. I did not come to bring peace, but a sword." It doesn't matter whether the people promoting false teachings are acting in good faith, it doesn't matter whether they are doing so in Christ's name, it doesn't matter whether they have a lot of followers, and it doesn't matter whether they are "doing good"
Looking at Catholicism from the outside is like occasionally visiting a local business. The owners are nice enough, the salespeople are polite, etc. They all are "good people" and seem to know what they're doing. However, if you examined the business' records in detail, you would realize that the business is headed for disaster because the people have made some fundamental errors and don't even realize it.
Similarly, to most Protestants, including most ordained Protestant clergy, Catholicism seems to be "routine Christianity" with a few add-ons, e.g., the Pope and a few more sacraments. This is because most Protestants (and most Catholics) don't study the official teachings of the Vatican, teachings Catholics are required to accept as given from God, under penalty of eternal damnation for anyone who refuses to believe them. (See The Facts on Roman Catholicism, a booklet available from Ankerberg Theological Research Institute.)