Re: 1 Corinthians 15:51-53. Listen, I tell you a mystery: We will not all sleep, but we will all be changed– in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed. For the perishable must clothe itself with the imperishable, and the mortal with immortality.
So when it says “at the last trump” how many trumpet sounds will there be before it, making it the last trump? No wonder Rosh Hashana is associated with the Rapture.
Paul said that he was disclosing a secret. ( the Greek phrase for “tell you a mystery” means to reveal a secret.) The secret was that some would not die, but would be taken alive into the Lord’s presence following an instantaneous transformation from mortal to immortal. The rapture happens fast. In one instant we’re walking on Earth and in the very next, we’re in the Kingdom.
Don’t try to use the trumpet reference in verse 52 to pin the timing down. There are several “Last Trumpets” in the Bible and Jewish tradition. For example, some theologians say there are two trumpets of God that recall the two horns of the ram caught in the thicket when Abraham went to sacrifice Isaac. They call the Trumpet of Exodus 19:16 the left one, or First Trump, and say that God will call the Israelites back to the Land in the End Times by blowing the right one, or Last Trump. Presumably this will happen at the time of the Battle of Ezekiel 38. If so then the rapture will occur around the time of this battle.
But to me his verse just means it’s the last trumpet we’ll hear before we’re changed. Since both the Corinthian passage and the one from 1 Thessalonians 4:16-17 describe the same things, it’s safe to assume that this trumpet is the same one mentioned in 1 Thes. 4:16 and is not pointing us toward any other event. So these two references both say that one generation of humans won’t die but will be suddenly changed from our earthly form to our heavenly one.
Also notice in 1 Thes. 4:16 Paul called this the trumpet call of God. The trumpets blown during the Feast of Trumpets are all blown by men on Earth and concern Israel, not the Church. The ones blown during the trumpet judgments of Rev. 8:6-9:20, and Rev. 11:16 are blown by angels in heaven, not on earth. And the trumpet blown in Matt. 24:31 summons the angels in heaven, not believers on earth. In my opinion the trumpet call of God is different from all these because it is blown at God’s command specifically to and for the Church on Earth.