Q. If we are in the end times 2 Thes. 2 speaks to a falling away. But Acts 2 seems to speak to an end times revival. Can you reconcile these two apparently contradictory verses?
A. In 2 Thes. 2:3 Paul said the day of the Lord cannot come until there has been a falling away (apostasy) and the man of lawlessness (anti-Christ) is revealed. He said this revealing will consist of him standing in the temple proclaiming himself to be God (2 Thes. 2:4). In Matt. 24:15 Jesus called this the abomination of desolation and said it will kick off the Great Tribulation. Then in 2 Thes.2:7 Paul said the anti-Christ cannot be revealed until the one holding the secret power of lawlessness back is taken out of the way. Pre-Trib scholars see this “restrainer” as the Holy Spirit, and His being taken out of the way away as a hint that the rapture of the Church will take place before the anti-Christ appears. However we don’t need to rely on this to prove the pre-trib rapture because in Romans 5:9 and 1 Thes. 1:10 Paul said the Church will be rescued (delivered) from (out of the time and place) of the coming wrath.
In Acts 2:17-21 Peter was quoting Joel 2:28-32 to show that the manifestation of tongues that had just taken place was the fulfillment of prophecy. In doing so he used the widest possible interpretation of the term “in the last days” to make it include the entire church age. But beginning in Acts 2:19 it’s clear the prophecy is about the end times judgments and in Acts 2:20 Joel’s reference to the Sun becoming dark and the moon turning to blood is repeated only here and in Rev. 6:12 in the 6th seal judgment. This is the event that will cause the kings of the earth to declare that the great day of God’s wrath has come (Rev. 6:15-17).
Acts 2:21 is the verse I assume you’re referring to as an end times revival. If so, it will happen after the time of God’s wrath has begun and after the Church has been raptured. I believe the rapture of the church will trigger a great revival on Earth as many of those left behind will realize the rapture proves the Bible to be right about the need to be saved. I see evidence of this in Rev. 7:9-10 where a multitude too large to count from every nation will arrive in heaven. Rev. 7:15 shows why this group can’t be part of the church. They will serve God day and night in His temple but they are not called priests, and there is no temple in the New Jerusalem where the church will be (Rev. 21:22).
I believe that a comparison of these two passages shows that both the falling away and the revival will take place.