Who are the 144,000 in the book of Revelation?

In Revelation 7.9-14, John saw a great worldwide revival commencing around the world (during the Tribulation). John wrote, "And I heard the number of those who were sealed. One hundred and forty-four thousand of all the tribes of the children of Israel were sealed" (Revelation 7:4).

These 144,00 are Jews, true witnesses of God and will be saved during the Tribulation. They will go out all over the world and bring the "great multitude" as mentioned in verse 9 to salvation in Christ because of their witness. During the Tribulation there will be so much fear that many who would not listen to believers before the Rapture and before the Tribulation began will finally listen to these anointed Jewish evangelists. God will protect these Jews so they can take the salvation message to the lost.

The 144,000 Sealed Jewish Evangelists

Revelation 7.1-8:

"After these things I saw four angels standing at the four corners of the earth, holding the four winds of the earth, that the wind should not blow on the earth, on the sea, or on any tree. Then I saw another angel ascending from the east, having the seal of the living God. And he cried with a loud voice to the four angels to whom it was granted to harm the earth and the sea, saying, "Do not harm the earth, the sea, or the trees till we have sealed the servants of our God on their foreheads."

And I heard the number of those who were sealed. One hundred and forty-four thousand of all the tribes of the children of Israel were sealed: of the tribe of Judah twelve thousand were sealed; of the tribe of Reuben twelve thousand were sealed; of the tribe of Gad twelve thousand were sealed; of the tribe of Asher twelve thousand were sealed; of the tribe of Naphtali twelve thousand were sealed; of the tribe of Manasseh twelve thousand were sealed; of the tribe of Simeon twelve thousand were sealed; of the tribe of Levi twelve thousand were sealed; of the tribe of Issachar twelve thousand were sealed; of the tribe of Zebulun twelve thousand were sealed; of the tribe of Joseph twelve thousand were sealed; of the tribe of Benjamin twelve thousand were sealed."