1. The successors of the apostles in the first five centuries of Christianity visibly and unmiraculously DISTORTED the Gospel in a universally and miraculously consistent and unified manner. (In other words, the early church was unified around its heresy.)
2. The successors of the Protestant reformers in the last five centuries invisibly and miraculously PRESERVED the Gospel in a universally and un-miraculously inconsistent and disunified manner. (In other words, the modern church is visibly disunified in its attempt to preserve the Gospel and possesses only an invisible unity, the nature/substance of which we can not be entirely certain.)
Neither proposition is true. The successors of the apostles faithfully passed on the truths that will never change (Jude 3). When the Protestant reformation occurred, the reformers left the "Household of God" and took some (not all) of its truths with them. As the camps outside the house have continued to split, Protestant denominations have found themselves with less and less truth, and less and less certainty that what they believe is true. Just like a plant withers when removed from the soil that sustains it, the truth withers when it is removed from its natural habitat, the One, Holy, Catholic, and Apostolic Church. Of course, the truth itself, being Jesus, never withers. We do well not to forget that Jesus and His Church are intimately and inseparably one. Of course, those elements of Catholic truth that have been preserved outside the visible bounds of the Catholic Church do not wither; in fact, they are the life-lines that keep non-Catholics connected with the mystical body of Christ. But these are also truths that the Catholic Church taught before the Protestant reformation ever occurred: Salvation by grace alone through Christ alone through faith (a faith that is alive and full of charity), the realities of heaven and hell, the virgin birth of Christ as well as his atoning death and resurrection. Protestants such as the Baptist pastors with whom I converse can not admit that the only truths non-Catholics have succeeded in preserving had already been preserved for 2,000 years in the Catholic Church. Thus, the Pastors find themselves in the difficult position of having to claim something that is in fact NOT true: the the Catholic Church teaches a false gospel. (I wish they could agree what that false gospel was--a gospel of works? a gospel of Mary?--but that's another story.)
Let us all continue to pray for the grace of conversion to submit ever more humbly and obediently to the teaching authority of Christ which Our Lord graciously bestowed upon the apostles and their successors so that we may know the truth, love the truth, live the truth, and die for the truth. "You are Kepha and upon Kepha I will build MY church!" (Matthew 16:18) "He who hears you [the apostles] hears me. He who rejects you rejects me." (Luke 10:16)
Praise be Jesus Christ, now and forever!