People see what they want to see. Most of us are taught what our parents and grandparents belived, and are given some sort of proof to back up the belief. Evangelical Protestants are taught Faith alone, and Scripture alone. Niether are supported by the Scirptures. However if you look through the Bible, you will find other verses that speak of being saved, or healed by our faith. If you carefully select those passages, and ignore the others you can easily distort what the Bible really says.
Many Evangelical Christians are taughe that they cannot accept or give any credence to what the Catholic Church teaches. They have been trained that the Catholic Church is not Chrisitan, so they will not listen with an open heart to what it really teaches. Another problem is that they learn “Proof Texts” which are individual verses they think “prove” the teachings they want to believe. Usually proof texts are isolated from the entire context of the Scriptures, and do not take the Scriptures as a whole story of God’s plan for the salvation of mankind.