The six seal judgments had been poured out, men ended up hidding in the rocks and the caves from wrath of God. Then God graciously gave to men and nations a pause, an opportunity to repent of their wickedness and rebellion against God which had brought on the judgments.
It is now the mid-trib point, a change is about to take place. For the first half of the tribulation antichrist has protected Israel, allowing her to rebuild the temple and to restablish the temple worship. The great change is described in Rev.12:7,8, we read about satan and his demons being cast out of Heaven. In verse 9, we read that satan is cast down into the earth. Satan launches into a new attack on Israel, see verse 13, from this point on satan uses every resource he has to utterly annihalate Israel.
God always counters satan, so at this point He seals the 144,000 Jewish evangelists as a guarantee that the remnant of Israel will be saved. Exactly how this seal will be affixed to their foreheads we are not told, and what the isignia will be we are not told.
Notice, it is only Jews that are sealed, a great multitude of Gentiles will be saved with some being martyred and some surviving to enter the Millenial kingdom in their natural bodies, but it is only Jews that are sealed. The tribulation period is a time when God is dealing with Israel. God is doing a special thing with Israel during that time. He is working to bring Israel back to Himself. Notice the number, 144,000 of all the tribes of the children. These 144,000 Jewish men will be witnesses to their own people. It is also quite probable that will be the leaders of Israel during the Millenial Kingdom.
Strange how that some believers say that God is finished with Israel. I believe one of the most serious errors of the church is the spiritualizing of the promises of God to Israel. Spiritualizing of the promises of God to Israel and ascribing them to the church, the blessings but not the curses.
RULE OF INTERPRETATION... God says what He means and means what He says. We do find types and symbols and figures of speech in the bible as we do in all literature. Treat the bible like other literature, when symbols and figures of speech are present it is easy to recognize them.
The sealing of the 144,000 Jews is simply God remembering HIs covenant with Abraham, Isaac and Jacob. God will not allow their annihalation during the tribulation period.
Again let me remind you that the tribulation period will not only be a time of awful judgment but it will be a time of redemption for an inumerable company of men and women. So in verse four we have the structure of the nation of Israel set before the King comes to reestablish the kingdom in righteousnes. In verses five to eight we have the tribes listed by name, God knows who the tribes are, they are not lost to Him.
The naming of the twelve tribes, in verses 5-8, is a witness that God is not through with the literal nation of Israel.
God has a program and a purpose for the future of Israel. He has a tribulation temple, a false temple that antichrist will desecrate and use for his own prupose. He has a nation to restore, he has a King to come and He has a millenial temple to build.