That is not the case; it is the basis of salvation and is much of the Mass. There are some add-ons that raise questions among those of us who have mixed religious training (I was baptized Catholic, raised Pentecostal, am married to a Catholic and a choir member and communicant in the Church). My core belief is that God looks upon the heart, not the form of worship.
My theory about Purgatory is that it is a "tradition of men" created with good intent: even though we are sinners saved by grace, if we fear the punishment maybe we'll sin a little less. I'm sure that HE will explain it to us later.
Find the Catechism of the Catholic Church on-line or find a copy and read from page 47 Paragraph 153, through page 53 Paragraph 165. It's spelled out there in great detail so as to avoid all sorts errors people have made over the centuries but it's also plenty clear enough for anyone to understand. The RCC very definitely does teach Salvation by Grace through Faith in Christ alone whether folks you're around teach that or not.
What the RCC does NOT teach because the Scriptures do NOT teach it is the bogus "once saved always saved" marketing slogan that Luther started. That's why confession of sins and the Grace that comes to us through the Eucharist is so important. It's not where our Salvation comes from, it's where the Grace to run the race all the way to our finish line comes from.
With all due respect, the questions that the "add-ons" raise are the signals that the RCC has developed its own "religion". There are no add-ons. Any add-on nullifies the view of Paul that salvation is by grace through faith, alone...