The 144,000 are spoken of in two places in the New Testament:

We find them the first time in Revelation 7 and the second in Revelation 14.

In Revelation 14 they are shown to us to be those who have been “redeemed” from the earth.

They are those, we read in Revelation 14, who are chaste. In verse 4 of the same chapter God says: “They are they which were not defiled with women, for they are virgins.” In other words, they’re the perfect bride of Christ. Their sins have been covered by the blood of Christ, and they stand before God as if they had never sinned.

The bible also tells us:

Revelation 14:4
“…These were redeemed from among men, [being] the firstfruits unto God and to the Lamb.”

We know that only the elect have been redeemed from among men, and this is the clearest statement we read which helps us to know the true identity of the 144,000.

So it is clear to see that they truly are the elect of God, the sheep chosen in Christ from before the foundation of the world.

“and in their mouth was found no guile.”

This too is talking about all born again believers. Christ’s perfect righteousness has been imputed to all those whom He represented and justified on the cross. They stand before God as if they had never sinned, as if they had never told a lie or spoken an evil word.

Now the number 144,000 is used because God frequently uses numbers symbolically. The number twelve is symbolical of the fullness of God’s program. And here He’s talking about the number of believers, the fullness of believers.

Sometimes He uses it as twelve plus twelve. And so we have the twenty-four elders in Revelation.

Sometimes He uses it as twelve times twelve. And so we have the 144,000.

Sometimes He uses it as twelve times twelve times twelve. And so we have the Holy City, the New Jerusalem, which is in size 12,000 stadia by 12,000 stadia by 12,000 stadia.

And in the Holy City Jerusalem, which is the fullness of all believers, we have twelve foundations, we have twelve gates, and we have walls that are 144 cubits thick. The whole picture, you see, is symbolical.

And so it is with the 144,000. It is the fullness of all believers.

In Revelation 7 they are spoken of as twelve tribes of Israel, because in the Bible God repeatedly speaks of the true believers as being the true seed of Abraham, whereas the blood descendants of Abraham are not necessarily Israel. The true Israel of God are those who are the believers in the Lord Jesus Christ. We read about such language in the epistle of Paul to the Galatians.

Galatians 3:29
And if ye be Christ’s, then are ye Abraham’s seed, and heirs according to the promise.

(Read the whole chapter of Galatians 3 for full context.)

Also we read in Galatians 6:

Galatians 6:14
But God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world.

Galatians 6:15
For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature.

Galatians 6:16
And as many as walk according to this rule, peace be on them, and mercy, and upon the Israel of God.

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(Adapted)