You're a bit wrong in your conclusion that every catholic would be saved, the reason being is that 1. They don't baptize which is immersion. The word baptize is transliterated from the Greek and means to dip, plunge, immerse. They pour water on you which isn't baptism. The Greek word for pour is different and not interchangeable. 2. They do the aforementioned on infants who are not believers. You must first believe and then be baptized. And infants have not committed sin and have no need of baptism.
Mark 16:15-16
15And he said unto them, Go ye into all the world, and preach the gospel to every creature.
16He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Belief + baptism = salvation