He is on that throne;
No...He isn't. He's sitting at the right hand of the Father in the Father's throne...expecting...
,that is why David foresaw the resurrection as the enthronement in Acts 2:30-31's interp of such OT passages
Nope. It says Christ was raised 'to sit', not 'is sitting' on David's throne.
This is where He is now:
Act 2:33 Therefore being by the right hand of God exalted,
This is 'when/then' He will reign from the throne of David:
Mat 25:31 When the Son of man shall come in his glory, and all the holy angels with him, then shall he sit upon the throne of his glory:
...which of course, 1P1P ignores.
This is also why the string of verses is there in Acts 13:32 about David and from Isaiah, and being made a Son, etc.
Just as it was necessary that Christ would suffer and rise from the dead because it is written that He would, in the same way it is written that Messiah shall reign from David's throne Jerusalem therefore it is necessary that it shall come to pass.
If one has as justification to alter what is written concerning David's throne then one would have the same justification to alter what is written concerning Christ's suffering and rising.
What justification do you have for a selective prophetical hermeneutic?
Luk 24:45 And He opened their understanding, that they might comprehend the Scriptures.
Luk 24:46 Then He said to them, "Thus it is written, and thus it was necessary for the Christ to suffer and to rise from the dead the third day,
Perhaps your understanding needs to be opened. Huh?
And why the raised fallen tent of David is the Gentile's faith right then in that generation.
I recommend you seeking the Lord Himself for understanding something that you obviously don't.
The tabernacle of David is inextricably connected to Messiah's reign from the throne of David.
Isa 16:5 In mercy the throne will be established; And One will sit on it in truth, in the tabernacle of David, Judging and seeking justice and hastening righteousness."
Acts 13 says this message of the resurrected Christ fulfilling everything of the promise to the fathers is a message that is for both Jews and Gentiles: v 26
Acts 13 does not say that Christ's resurrection was the fulfillment of everything promised to the fathers.
It says that according to the promise GOD has raised up unto Israel a Saviour.
That by condemning Him a prophecy was fulfilled
Act 13:23 Of this man's seed hath God according to his promise raised unto Israel a Saviour, Jesus:
Act 13:27 they have fulfilled them in condemning him.
Act 13:28 And though they found no cause of death in him, yet desired they Pilate that he should be slain.
Act 13:29 And when they had fulfilled all that was written of him, they took him down from the tree, and laid him in a sepulchre.
Act 13:30 But God raised him from the dead:
Then it says that all that was written of Him was fulfilled in His suffering and death but His being taken taken down from the tree, laid in a tomb and then raised is stated to have taken place after 'all that was written of Him' was fulfilled.
No doubt, His being taken down, laid in a tomb and being raised from the dead was also written and fulfilled, however the text does not include those details as part of what is said to be fulfilled in vs 27 and vs 29.
Act 13:32 And we declare unto you glad tidings, how that the promise which was made unto the fathers,
Act 13:33 God hath fulfilled the same unto us their children, in that he hath raised up Jesus again; as it is also written in the second psalm, Thou art my Son, this day have I begotten thee.
Act 13:34 And as concerning that he raised him up from the dead, now no more to return to corruption, he said on this wise, I will give you the sure mercies of David.
The promise made to the Fathers in vs 32 concerns Messiah's resurrection, receiving the sure mercies of David and His being begotten. It does not say that it concerns all of what was written in prophecy about Him and certainly doesn't say that all prophecy concerning Christ has been fulfilled.
You are reading something into the text that is just not there.
Act 13:37 But he, whom God raised again, saw no corruption.
Act 13:38 Be it known unto you therefore, men and brethren, that through this man is preached unto you the forgiveness of sins:
Act 13:39 And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses.
Then Paul shifts to the message of forgiveness of sins unto all that put their trust in Him.
With regard to prophetic Scripture, Christ said that since it is written then it is necessary that it be fulfilled.
There is a whole lot of prophecy that has been written that has not been fulfilled....yet.
There are no if's or maybe's in this regard.
It is necessary that it will be.