I’m sure the apostles knew what was up once the Holy Spirit dropped.
They knew something was happening, however, they may not have understood the scope of the church, which was not mentioned in the Old Testament, but was a mystery, and the church age. Just as Jesus didn't come as the end of the world, but had to die first, return to heaven while His church was built, and then return at a later time. Even in Matthew 24 it said that the gospel would reach the whole world, all the nations, before the end.
And a promised return to those in that day to a day which would never be so great again happened.
He promised to return, and He will. He is still building HIs church, and it still awaits, or is in the midst of, the great falling away, the great deception. The church is at the point where many aren't even bothering to defend against false teachings anymore. They welcome it with open arms.
Of course it’s by faith I believe so. No proof needed.
Some continuously say for each and every generation this supposed great and dreadful day is suppose to happen but it wasn’t written to us but those twelve tribes in that day.
The New Testament was written for the church, so includes today. However it is true that we must never forget the audience, or well will miss some of the meaning. Such as, when it says women are to be silent in the church, doesn't mean to tell them to shut up. It has to do with what was happening in that particular church at that time. The women were disrupting the service, interrupting the pastor/preacher/teacher to ask questions. Paul was simply saying the women were not to disrupt the service. Instead, ask their husbands at home. Paul put the husbands on notice. Just as they were to ask their husbands at home, they were to be able to answer... The spiritual head of the family.
Jesus is returning, and it will be at the end of the church age. Two parts of one program. The redemption of Israel the nation (that is the elect that are still within), and the redemption of the church (Jew and Gentile believers in the church.) Daniel speaks of the Kingdom coming to Earth when the rock destroys the statue that is the image of the times of the Gentiles, and the four great empires. Nebuchandezzar (as the gold head represents him, not Babylon), the Medo-Persian empire, the Greek Empire, and Imperialism, which started with Rome. The Colonial period was all about Imperialism. And then the newly formed Unitted States of America just happens to choose a government based on the Republic of Rome. What goes around comes around.