Why do the 144,000 preach the gospel of the kingdom instead of the gospel of grace?
The 144,000 are young Jewish men whose tribal lineage God has kept intact. They preach the gospel of the kingdom, not grace, because the gospel of grace has ended; the church is gone, and God has resumed His program with Israel, proclaiming the coming King.
Les explains that these are 144,000 young Jewish men, 12,000 from each tribe, whose tribal lineage remains intact enough for God to identify them by tribe. He teaches that they will go around the globe preaching the gospel of the kingdom, not the gospel of grace, because grace has ended and the church is gone. God is right back where He left off with Israel, as in the early part of Acts, and these men proclaim the coming of the King.