As I stated above, all Protestants must ultimately trace their theological roots to one or another schism from the Catholic Church. Muslims and Jews never were part of the Church, so they cannot be said to be causing disunity within it.
There is a bunny trail related to this thread, and as the OP, I am claiming the right to chase this rabbit, since it is tangentially connected to my original purpose, which was to discredit one of the “reformers’” theological tenets.
When I was a Protestant, my interpretation of Church history was to compare the Church that Jesus founded to a train. In 33 A.D. (or 30, if you prefer), that train left the station, bound for, say, Miami (any actual similarity between Miami and Heaven is purely coincidental; this is only an illustration). However, at some point (say, in the 4th century), everyone on the train fell asleep. 1200 years later some German, French, and English theologians, politicians, and monarchs woke up and discovered that while they were asleep, someone had shunted the train onto a different track, and it was now en route to, say, Chicago (any actual similarity between Chicago and Hell is also purely coincidental). They succeeded in detaching some carriages, co-opted another locomotive, and set part of the train back in the direction of Miami.
Then while I was still a serious Protestant (about 10 years before my conversion), I bought a CD-ROM entitled the Master Christian Library. It was a Protestant production, but it also contained some Catholic classics, such as St. Thomas Aquinas’ Summa Theologica, AND the full 37-volume set of the Church Fathers. I started reading Volume I of the Fathers, and I remember very clearly thinking, “Wow! St. John isn’t even cold in his grave, and already the Church has fallen into the Catholic heresies.” This Church was apostolic, authoritative, liturgical, and eucharistic, not at all what I was used to. Reading the Fathers started a slow process that culminated in my confirmation as a Catholic in 2005.
In the course of my conversion, I had to rethink my “train” analogy. The re-routing of the train from Miami to Chicago was my charitable (???) way of saying that at some point (in my opinion at the time, in the 4th century), the Church had apostatized. However, Jesus said (Matt. 16:18) that the gates of Hell would not prevail against the Church that he would build. He also said to his Apostles in the Upper Room Discourse (John 16:13) that the Holy Spirit would guide them (and, necessarily because they would not physically live forever, their successors) into all truth.
If the Church that Jesus founded did in fact apostatize, then the gates of Hell prevailed, and the successors of the Apostles were led into something other than the truth, and Jesus is proven to be either a liar or mistaken. If Jesus was a liar or mistaken, then He was only a man, not the Son of God, and all Christianity is a 2000-year-old fraud.
On the other hand, if Jesus was God in the flesh, then He could not have been either a liar or mistaken. The Church He founded could not have been overcome by the gates of Hell, and the successors of the Apostles could not have been led into error. The Catholic Church could not have apostatized, which means that it is those who split from the Catholic Church who are in error and schism, and who therefore must find themselves in violation of God’s will concerning the unity of His Church.
Just a little something to think about.
DaveBj
