The Feast of Trumpets teaches us that Jesus Christ will visibly return to the earth at the end of this age. At that time He will resurrect the saints who are no longer living and instantly change those saints who are still alive to immortal spirit beings (Matthew 24:31 Matthew 24:31And he shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.
American King James Version×; 1 Corinthians 15:52-53 1 Corinthians 15:52-53 [52] In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed. [53] For this corruptible must put on incorruption, and this mortal must put on immortality.
American King James Version×; 1 Thessalonians 4:13-17 1 Thessalonians 4:13-17 [13] But I would not have you to be ignorant, brothers, concerning them which are asleep, that you sorrow not, even as others which have no hope. [14] For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him. [15] For this we say to you by the word of the Lord, that we which are alive and remain to the coming of the Lord shall not prevent them which are asleep. [16] For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: [17] Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
American King James Version×). This festival commemorates the blowing of the trumpets that will precede His return. Seven angels with seven trumpets are described in Revelation 8-10. Christ will return with the blowing of the seventh trumpet (Revelation 11:15 Revelation 11:15And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
American King James Version×). The Feast of Trumpets depicts the return of Jesus Christ to earth to establish the Kingdom of God.

To read more about the Feast of Trumpets click the links below.

http://www.ucg.org/tags/feast-of-trumpets

The Feast of Trumpets: A Turning Point in History

The Exciting Feast of Trumpets