There are several differences between Catholics and Protestants. Some differences are that: One of the biggest difference between Catholicism and Protestantism is the issue of the sufficiency and authority of the bible. Protestants believe that the Bible by itself is the source of God’s revelation to mankind and teaches us all what is needed for our salvation from sin. Protestants view the Bible as the standard that all Christians must behave like. But Catholics do not believe that the Bible alone is sufficient. They believe that both the Bible and sacred Roman Catholic tradition are equally binding upon a Christian.