How do believers in the Great Apostasy reconcile their views with Matthew 16:18?

From the Wikipedia article on [the Great Apostasy](https://en.wikipedia.org/wiki/Great_Apostasy) : > The Great Apostasy is a concept within Christianity, identifiable at least from the time of the Reformation, to describe a perception that the early apostolic Church has fallen away from the original faith founded by Jesus and promulgated through his twelve Apostles. Protestants used the term to describe the perceived fallen state of traditional Christianity, especially the Catholic Church, because they claim it changed the doctrines of the early church and allowed traditional Greco-Roman culture (i.e., Greco-Roman mysteries, deities of solar monism such as Mithras and Sol Invictus, pagan festivals and Mithraic sun worship and idol worship) into the church on its own perception of authority. Because it made these changes using claims of tradition and not from scripture, the church – in the opinion of those adhering to this concept – has fallen into apostasy. A major thread of this perception is the suggestion that, to attract and convert people to Christianity, the church in Rome incorporated pagan beliefs and practices within the Christian religion, mostly Graeco-Roman rituals, mysteries, and festivals. For example, Easter has been described as a pagan substitute for the Jewish Passover, although neither Jesus nor his Apostles enjoined the keeping of this or any other festival. > > The term is derived from the Second Epistle to the Thessalonians, in which the Apostle Paul informs the Christians of Thessalonica that a great apostasy must occur before the return of Christ, when "the man of sin is revealed, the son of destruction" (chapter 2:1–12). The Catholic Church, Anglican Church, Eastern and Oriental Orthodox Churches have interpreted this chapter as referring to a future falling-away, during the reign of the Antichrist at the end of time. However, Jesus said: > And I tell you that you are Peter, and **on this rock I will build My church, and the gates of Hades will not prevail against it.** (Matthew 16:18 BSB) **Question**: According to believers in the Great Apostasy of the Church, how can there be a Great Apostasy if the Church is built on a rock against which the gates of Hades shall not prevail?