Our separated [non-Catholic Christian] brethren hold much Christian truth, but not all of it. We might compare their religion to a stained glass window in which some of the original panes were lost and have been replaced by opaque glass: Something that was present at the beginning is now gone, and something that does not fit has been inserted to fill up the empty space. The unity of the original window has been marred.
When, centuries ago, they split away from the Catholic Church, the theological ancestors of these Christians eliminated some authentic beliefs and added new ones of their own making. The forms of Christianity they established are really incomplete Christianity.
Only the Catholic Church was founded by Jesus, and only it has been able to preserve all Christian truth without any error—and great numbers of people are coming to see this.
The difference is over authority in the Christian faith. Protestants reject the authority of the Pope and Magisterium. Many reject the tradition of the church all together. (Anglicans, Lutherns, and some branches of Methodism hold tradition as an authority as long as the bible explicitly backs it up.) Other denominations view the Bible as the only authority, if it isn’t implicity written in the Bible, you shouldn’t believe in it.
Catholics and the Eastern Orthodox view captial “T” tradition as another source of Revelation and authority. When we speak of tradition we mean that our teachings are the teachings of the Apostles handed down by their succesors aka “Bishops”.
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