The “gospel of the kingdom of God”, is the “gospel of salvation”. But, how are they synonymous? Please follow me on this progression of “mocking” thought by Isaiah, “precept upon precept, line upon line, here a little, there a little” (Isa 28:10, 13).
Remember, that mankind was made in the “image” (or likeness, and it was so) of YHVH Elohim (Gen.1&2) to have (future) dominion (radah,to subjugate) over all earth (Gen.1:26-28). Moreover, that the “world to come” will not be “subject” (again) to angels but to mankind (Heb.2:5-18). And also, that the Lamb was “slain from the foundation of the world” (Rev.13:8). Indeed, it goes back even before the beginning of this world.
There is this strategic plan that while God did not like mankind to sin, man was created “very good” but still mortal and can die, even without sinning. He was “very good” as a “formed clay” but still “incomplete” as God will re-visit this “marred clay” as a potter can do to any clay to make it better, into “another vessel”(Jer 18:4).
However, in the garden of Eden, Adam sinned against God’s commandment, “thou shall not eat of the fruit of the tree of knowledge of good and evil.. as he would surely die”(Gen.2:17). What death was God referring to? Notice this, “As it was once appointed that man would die and after that, the judgment” (Heb 9:27), therefore everyone will die (naturally, being mortal) then be resurrected to be judged as to the final destiny: “eternal life or “eternal death”.
The death therefore that God was referring to in Gen 2:17 was not “mortal death” that everyone was “once appointed” to be resurrected from. It has to be “eternal death”, from which there is no resurrection. The sin of Adam warrants eternal death not mortal death. Mankind will all die being mortals and be resurrected, but will be facing the judgment of eternal life or eternal death. The sin of Adam has a consequence of “eternal death” from which by substitution was imputed to the death of Jesus. That death of Jesus could have been eternal had it not been for the promise of Father God that Jesus would be resurrected. The faith (of) Jesus (in) the Father is anchored securely on this. Jesus’ death was an imputation for the “eternal death”, not the physical or mortal death. As Jesus was resurrected from what could have been “eternal death”, so shall those who follow Jesus as he is “bringing many sons to glory” (Rom 2:10).
The sin of Adam is punishable with “eternal death” that would have separated mankind “eternally” from the Father. The God of Gen 1 & 2, the YHVH ELOHIM/Lord God has to incarnate and die so that mankind would be reconciled to the Father. But, his death was only for reconciliation, not for salvation. Instead, we are saved “by his life”, i.e., Jesus has to be resurrected, for what? Notice, John 16:7 and John 14:16, 26 that he has to be resurrected to “life”, so the Holy Spirit will be sent to us “to dwell” in us (Acts 2). Why should the H.S. dwell in us? So that we will power (Acts1:8) and for sanctification (1Pet.1:2;RoRom 15:16; Cor.6:11; II Thes 2:13).
This HS provides spirit-power for “cognition, conviction, affection” and “oneness” with God. As circumcision is a “seal” to identify Israel, so is the HS a seal (Jn.6:7;2 Cor 1:21-22; Eph 1:13-14; 4:30; 2 Cor 5:5.
This HS prepares us to have the “mind of Christ”, so that at resurrection and endowed with spirit-body we will “be like him” and no longer just “an “image” (Gen 1) but co-substance with God.
Finally, “salvation” is about becoming a “new creation”, a “kingdom of God”. When God created living things, he created angelic-kingdom, plant-kingdom, and animal-kingdom. But, when it came to “man”, God was not creating a “human kingdom”, instead, God was creating a kingdom composed of spirit beings “like him”, a ” kingdom of God” and above angelic beings. The kingdom of God is more than just a “government of God” and a place. It is a “new creation”.
What an awesome gospel and destiny of man