Thought from Today's Old Testament Passage:
Blow ye the trumpet in Zion, and sound an alarm in my holy mountain: let all the inhabitants of the land tremble: for the day of the Lord cometh, for it is nigh at hand [Joel 2:1].
What is the significance of the blowing of the trumpet? Back in the Book of Numbers we learn that when the children of Israel started through the wilderness, God commanded them to make two silver trumpets. He gave the instructions to Moses: "And the Lord spake unto Moses, saying, Make thee two trumpets of silver; of a whole piece shalt thou make them: that thou mayest use them for the calling of the assembly, and for the journeying of the camps" (Num. 10:1-2). When Israel was in the wilderness, God used the trumpets to move them on the wilderness march. The first blowing of the trumpet was a signal that everybody should get ready to march. When the pillar of cloud would lift and move out, they would take down the tabernacle. Then immediately the trumpet would sound again, and Moses and Aaron would move up front ahead of the tribe of Judah, and the ark would go out ahead with them....
Now when we come to Revelation, the final book of the Bible, we find the blowing of the trumpets again. Although some expositors feel that this is in relation to the church, there is no blowing of the trumpet for the church. The sound of the trumpet at the time of the Rapture (1 Thes. 4:16) will be the shout of Christ Himself: "For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God …"—His voice will be like a trumpet.
J. Vernon McGee, Thru the Bible Commentary [computer file], electronic ed., Logos Library System (Nashville: Thomas Nelson) 1997, © 1981 by J. Vernon McGee.