Many theologians have written about the apostasy as if it were an end-of-the-world event. They say that before the return of Christ, there will be a departure from the faith in the churches. That many will leave the churches and will become as the world.
The truth is that the Apostasy started at the cross. Christ warned His disciples about false Christs, and all the apostles in their letters also admonished the believers to beware of false teachers that would come into their circle unawares and would try to deceive them.
The apostasy was prophesied by Daniel in chapter 9. Christ told His disciples to go and read Daniel. He opened the book of Daniel that had been sealed for almost 500 years, so they could understand the reality of the Messiah coming and establishing His kingdom, and also the warfare that would follow afterwards.
Damiel said that the truth was going to be trampled down under foot by the enemies of Christ led by Satan, and that they would prosper. John in his first letter said that the apostasy was already at work.
The apostasy has been on earth since the death of Christ, because Satan was loosed from his prison at the cross. The accounts in Revelation that talk about Satan being defeated and being freed from prison occurred at the same time, at the cross.
Christ destroyed the power of the Devil, but He also let him loose to continue deceiving a wicked and cursed world that wants nothing to do with God. That’s the reason why evil prospers in this world without apparent restrain. God has allowed it, to test His people like gold is tested.
Believers do not dispair, because we know that Christ has overcome Satan and the world, even when the world seems to have the upper hand.