I'm going to take a crack at this. Please don't make me regret doing so...
I disagree that after the church( His body, His Bride) is removed from this Earth, the dispensation of Grace will disappear.
Right off the bat the errant premise presents itself. Which is it, Bladerunner, His body or His Bride? I can't be both (an analogy made by Paul not withstanding, by the way.)
Israel is the Bride of Christ, we are NOT Israel, we are the Body of Christ. These are not the same thing. Thinking they are the same thing leads to confusion and errors. Errors such as denial of the rapture, for example.
(I find out several minutes after reading this first line of yours that you do not deny the rapture. I'm leaving the above intact because I cannot reconcile the contradiction.)
For as in the beginning, it is by the Grace of God that mankind is still here. Abraham never formally knew what the laws of Moses were. By the Grace of God is the only thing that salvation comes from.
This is false - as stated. It is grace that kept Adam and Eve alive to produce the human race and it is true, albeit irrelevant that Abraham didn't know the law of Moses but lots and lots of people did and do know the law of Moses!
Why is Abraham and not Moses pointed to as the father of the whole household of faith? Because God entered into TWO covenants with Abraham. In the first Abraham sacrificed a whole bunch of animals, splitting them in two and placing half on one side and half on the other. Then God put Abraham into a deep sleep and passed through the sacrifice ALONE. This is the covenant of grace. Abraham had no terms to meet in this covenant because he was unconscious when it was consummated.
In the second, the covenant of circumcision, I can assure you that not only was Abraham FULLY awake but the covenant had a very distinct work of the flesh THAT WAS REQUIRED! Moses comes along and, under the same covenant, adds the Ten Commandments and from there the entire rest of the law was added, all of which was just as required as circumcision, which came first because it, being a physical cutting off of the flesh, is symbolic of the whole law, it being a cutting off of our fleshly desires. We can know for maybe just shy of a thousand reasons that obedience to the law was required but what has to be the clearest proof is the fact that God was coming to kill Moses himself because he had failed to circumcise his son. That sort of makes obedience to the law come off as being required to me!
Much later, Israel, the Circumcision, the People of the Law, were cut off (see Romans 7-9) leaving only the covenant of Grace. God turned away from Israel and toward the gentiles through Paul with the Dispensation of Grace forming the Body of Christ which functions purely and entirely on the basis of grace through faith apart from works. A point that is so different from the Law that the Twelve had a hard time getting it to sink in. Paul was sent to Israel by God to explain his gospel to them and then later, Paul, when the men from James showed up, had to get in Peter's face in defense of the liberty Paul's followers had under grace.
The 'Everlasting Gospel' will be the law from the time after the Rapture to the time of Eternity which includes the millennium to come.
So which is it, Bladerunner? Is there a rapture or not? Just what is it you think the rapture is if no one is removed from the Earth? Just were are we going to be after we get raptured?
During this time, there will be multitudes of those that show their faith in Jesus by losing their heads (literally). For after the Pre-Trib Rapture event happens and it will happen, there will be for a short period of time, no one left on earth above ground or below ground that believes in Jesus Christ..Those that die during this period of time, formally known as the 'tribulation' saints are brought on by the 144,000 Jewish ministers, the Angel (carrying the Everlasting Gospel) and the two witnesses all sent to earth to preach the Everlasting Gospel to those that would come to believe in Jesus Christ during Daniel''s 70th week.
That gospel will be practically identical to that preached by Peter in Acts 2...
Acts 2:36 “Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.”
38 Then Peter said to them, “Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit. 39 For the promise is to you and to your children, and to all who are afar off, as many as the Lord our God will call.”