Catholics want it MORE COMPLEX ... I know ... LOL ...
Salvation is simple, though ...
Romans 10 ...
8 But what does it say? “The word is near you, in your mouth and in your heart” (that is, the word of faith which we preach):
9 that if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved.
10 For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation.
11 For the Scripture says, “Whoever believes on Him will not be put to shame.”
12 For there is no distinction between Jew and Greek, for the same Lord over all is rich to all who call upon Him.
13 For “whoever calls on the name of the Lord shall be saved.”
“Whoever believes on Him will not be put to shame.”
“believes in HIM” i.e. His TEACHING. For this purpose Christ established ONE Church and commanded Peter and his successors to “Go forth and TEACH...”
Presumably this is to TEACH ONE Truth.
Not every Tom, Dick, and Harry gets to crack open the pages of the Bible and authoritatively interpret scripture. That authoritative interpretation was directed specifically to Peter and his successors. When Christ said “Feed my lambs, feed my sheep..,” it was directed specifically to Peter in the presence of the other apostles.
The direction was not to all. Peter was the new head of the Church established by Christ. The successors to Peter form an unbroken line of authority. This is why the canonical texts we use today were officially the identical texts ratified in manner, form, and selection by the Synod of Rome in AD 382. What greater authority than poring over hundreds of written manuscripts and fragments, including some, and discarding others, and then pronouncing that what the Catholic Church deemed authentic inspired by the Holy Spirit as the true word of God.
This authority did not fly out of the window at some late point in time. No one gets to authoritatively interpret the Word of God except the Catholic Church, and its rituals, liturgies, and forms of worship of veneration. The authority was absolute. “WHATSOEVER, thou shall bind on earth shall be bound in heaven...”