1 Corinthians 15:51 Behold! I tell you a mystery. We shall not all sleep, but we shall all be changed, in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised imperishable, and we shall be changed. For this perishable body must put on the imperishable, and this mortal body must put on immortality.
1 Thessalonians 4:14-17 For since we believe that Jesus died and rose again, even so, through Jesus, God will bring with him those who have fallen asleep. For this we declare to you by a word from the Lord, that we who are alive, who are left until the coming of the Lord, will not precede those who have fallen asleep. For the Lord himself will descend from heaven with a cry of command, with the voice of an archangel, and with the sound of the trumpet of God. And the dead in Christ will rise first. Then we who are alive, who are left, will be caught up together with them in the clouds to meet the Lord in the air, and so we will always be with the Lord.
2 Peter 3:10 But the day of the Lord will come like a thief, and then the heavens will pass away with a roar, and the heavenly bodies will be burned up and dissolved, and the earth and the works that are done on it will be exposed.
Matthew 24:31 And he will send out his angels with a loud trumpet call, and they will gather his elect from the four winds, from one end of heaven to the other.
In the Biblical sense, a mystery is simply a thing to be understood by spiritual, rather than by merely human perception. Paul will tell the Corinthian Christians something they could not have known by reason or research. They could not have known this unless God revealed it to them.
In a single moment, Jesus will gather His people (both dead and on the earth) to Himself, for resurrection. There will come a day when in God’s eternal plan, He gives those dead in the Lord their resurrection bodies, and then in an instant He gathers all His people to meet Jesus in the air. All the redeemed on the earth at that time will rise up to meet the Lord in the clouds, and will receive their resurrection bodies. Ironside says that the last trumpet was a figure of speech that came from the Roman military, when they broke camp. The first trumpet meant, “strike the tents and prepare to leave”; the second trumpet meant, “fall into line”; the third and last trumpet meant “march away.”
Are you anticipating the last trumpet? Are you ready to hear it? Are you ready to face death and enter eternity? Surrender your entire life to humbly serve, honor, follow, obey, trust, and rely in Jesus Christ. There is no other way to enter eternity in heaven.