"And this gospel of the kingdom shall
be preached in all the world for a
witness unto all nations; and then
shall the end come."Matthew 24:14

This Gospel that will be preached to
the ends of the Earth will be the
Gospel of the Kingdom.

Chapter 7 of Revelation tells us that
there will be 144,000 Jewish witnesses
and numerous Gentiles who will preach
this Gospel of the Kingdom.

Those receiving this Gospel during the
Tribulation will be martyred(beheaded)
for the witness of Jesus.