I have a calling to proclaim the Gospel of the Kingdom. It is the gospel Jesus primarily preached. Originally it was preached to Jews only. But the Jewish nation rejected the offer of the Kingdom with Jesus Christ as their King because a suffering savior did not meet their expectations.
For nearly two thousand years, the offer of the Kingdom has passed to any who have trusted Jesus Christ for salvation. The Kingdom age is near at hand, and you must be prepared for it in order to be able to enter. First, you must be born again with a new spirit begotten of God. (John 3:3) That is purely a work by God in us when we first believe in Jesus. Anyone with a regenerated spirit will never perish, though they may physically die. Second, to inherit the 1000-year reign of Christ on the earth, you must give up your life (will, lusts, selfishness) in order to gain life in the coming Millennium.
Eternal salvation is free, received through faith in Jesus Christ. The Millennium is earned by surrendering your self (soul) completely to God for his glory.