Why did this happen?
It is a combination of two things.
It was part of God’s plan.
Christ the fulfillment of the old testament was crucified and then resurrected.
The church or “Bride of Christ” that replaced the Old Testament Jewish Church was to be crucified and then resurrected. (Note: Pacumeni is writing a book on this. He has some interesting ideas that may or may not fit exactly with what I have put together here.
The times dictated it would happen.
Just as hinted to above, the Restoration came forth at exactly the time and place God intended for it to come forth. In a country that had a constitution that protected the personal expression of religion, the restored church was brutally persecuted. Were the restoration to have occurred in a less free country, the divine intervention required to sustain it, while not an impossibility, would have created wonders that were not in accordance with Gods plan.
The perfect time and place for the Restoration was similarly in its perfection to the perfection of the time for Christ’s coming. The millennial time was perfect for the Birth of Christ, the Birth of his Bride, the Death of Chirst, the Resurrection of Christ, and the Death of his Bride (but the survival of his record).
This time was unique in all of history (just as the Restoration time was unique). God became man and mankind killed their God. This in itself makes for a unique time.
Without Pax Romanus, the Apostles would not have been able to roam the world teaching of Christ (it wasn’t safe for them then, but previous and subsequent times have enjoyed much greater boarder disputes). This huge Jerusalem thing might not have made it out to the world (God could do all, but he usually does it through willing and sometimes unknowing humans who are part of his divine plan).
The initial persecution of the church by the Jews was harsh. The rule imposed by the Romans probably afforded the Christians with a little protection (remember capital punishment was reserved for the Roman government).
The ultimate acceptance of Christianity by the Roman Emperor protected the Bible and Christianity effectively forever. This is a divinely chosen time.
One could either argue that this perfect time had a side effect associated with the Apostasy or as I would say this perfect time included the perfect time for an Apostasy also.
Persecution of Christians was intense. Christians died, Christians denied, and Christians sat silently rather than teaching the glorious truth. Converts where had, but sometimes at the cost of perverting the gospel. And without the advances of modern communications, it was easy for gospel truths to drift. All these things lead to the apostasy. It was all part of the perfect time and place.
List to follow.