As for the great gulf, I would say is death itself, from the law. But I never thought about that one much. Good question though. The reason I say death itself, is because of this.
Concerning the resurrection......
Mat 22:31 But as touching the resurrection of the dead, have ye not read that which was spoken unto you by God, saying,
32 I am the God of Abraham, and the God of Isaac, and the God of Jacob? God is not the God of the dead, but of the living.
33 And when the multitude heard this, they were astonished at his doctrine.
Also corresponding to the eternal nature of the ORDER of Christ as our high priest.
1 For this Melchisedec, king of Salem, priest of the most high God, who met Abraham returning from the slaughter of the kings, and blessed him;
4 Now consider how great this man was, unto whom even the patriarch Abraham gave the tenth of the spoils.
2 To whom also Abraham gave a tenth part of all;
6 But he whose descent is not counted from them received tithes of Abraham, and blessed him that had the promises.
7 And without all contradiction the less is blessed of the better.
8 And here men that die receive tithes; but there he receiveth them, of whom it is witnessed that he liveth.
24 But this man, because he continueth ever, hath an unchangeable priesthood.
25 Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.
And as for the covenant.
Take note of what is spoken to Abraham personally, in the 1st covenant in verse .
12 ¶ And when the sun was going down, a deep sleep fell upon Abram; and, lo, an horror of great darkness fell upon him.
13 And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years;
14 And also that nation, whom they shall serve, will I judge: and afterward shall they come out with great substance.
15 And thou shalt go to thy fathers in peace; thou shalt be buried in a good old age.
16 But in the fourth generation they shall come hither again: for the iniquity of the Amorites is not yet full.
17 ¶ And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces.
18 In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land,
Abraham was told he was going to die. The promise of his in heritance in the land HAD ALWAYS BEEN AFTER HE HAD DIED.
Therefore Abe, Isaac, and Jacob and Joseph all looked to the resurrection to attain the promises. For the inheritance that was to the seed in this life was to the 4th Generation.
