Revelation 14:1-5

Revelation 14:1: “And I looked, and, lo, a Lamb stood on the mount Sion, and with him an hundred forty and four thousand, having his Father’s name written in their foreheads.
2 And I heard a voice from heaven, as the voice of many waters, and as the voice of a great thunder: and I heard the voice of harpers harping with their harps:
3 And they sung as it were a new song before the throne, and before the four beasts, and the elders: and no man could learn that song but the hundred and forty and four thousand, which were redeemed from the earth.
4 These are they which were not defiled with women; for they are virgins. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men, being the firstfruits unto God and to the Lamb.
5 And in their mouth was found no guile: for they are without fault before the throne of God.”

It looks like the 144,000 witnesses are only going to minister during the first half of the Tribulation. At some point in the middle of the Tribulation they are all going to be killed, so they will not be around during the second half of the Tribulation. It seems that when it said in the previous chapter that the Beast was given the power to overcome the saints, that included power over these witnesses.

God praises these witnesses very highly as being people “without fault” and without guile. These Jews are dedicated to Jesus and follow Him wherever He goes. They are His faithful servants. For their faithfulness they are given a special place in Heaven and a special song to sing. The witnesses did well, they were faithful, they accomplished their task, and no fault was found in them.

This passage calls them the firstfruits. One of the purposes of the Tribulation is to draw the Jews back to God. These 144,000 are all Jews, so perhaps that is what it means – this is the first large group of Tribulation Jews to come to Christ. Eventually the whole nation will return, but this group is first.

It’s worth noting that this group is distinct from the church (which was represented by the 24 elders). The witnesses are not a part of the church; they are a different group altogether.