The Great Apostasy the Restoration requires did not happen: the earliest Christian sources show continuity on the core doctrines, and the teachings said to have been lost are absent from them rather than suppressed.

The load-bearing claim of the whole system is that after the apostles died, the true church and its authority disappeared from the earth for roughly seventeen centuries, until God restored them through Joseph Smith beginning in 1820. This is not a claim to be one denomination among many; it is a claim that Catholic, Orthodox and Protestant Christianity lacked valid authority for all that time, so it carries a large burden of proof. The Christian reply has three parts. The second-century sources (Ignatius, Clement, Justin, Irenaeus) show continuity of teaching on the core doctrines, not a collapse. Jesus promised that the gates of hell would not prevail against his church. And the specific doctrines said to have been lost (an embodied Father, exaltation, temple ordinances) are absent from the earliest Christian sources rather than present and then suppressed, which is what one would expect if they were never there. The church’s own statements of the claim are the exhibits, so that it is tested in its own words.