The pure form of Christianity is based solely on God's word the Bible, so the question is what does the Bible teach? And the Christian Greek scriptures while saying a little about what would have happened don't talk much about it and that is because the Hebrew scriptures already foretold what was going to happen when the Messiah appeared.
Daniel gave a prophecy of 70 weeks of years. In it Jehovah God reveals when the Messiah would appear and what would happen to him. And in turn he foretells what would happen to Jerusalem and the temple, the second temple, and this was when Daniel was in Babylon and the second temple hadn't even been built yet:
"You should know and understand that from the issuing of the word to restore and to rebuild Jerusalem until Mes·siʹah the Leader, there will be 7 weeks, also 62 weeks. She will be restored and rebuilt, with a public square and moat, but in times of distress.
“And after the 62 weeks, Mes·siʹah will be cut off, with nothing for himself."
-Daniel 9:25, 26.
It is important to establish these facts then we will read the following verse in Daniel's vision telling us what had already been decided upon for Jerusalem and the second temple that was to be built and would be in existence when the Messiaah appeared on earth.
Firstly the call that went forth to rebuild Jerusalem happened in 455 B. C. E. You can use the book of Nehemiah to determine this. Nehemiah 2:1-8 shows us that Artaxerxes Longimanus granted him permission to return to Jerusalem to rebuild its walls and the gates of the city. It says that this happened in his "20th year:"
"In the month of Niʹsan, in the 20th year of King Ar·ta·xerxʹes..."-Nehemiah 2:1.
Counting from the 20th year of King Artaxerxes which was in 455 B. C. E. 69 weeks of years you come to the year 29. C. E. That is when Jesus was baptized with holy spirit and began the preaching work of God's kingdom. Daniel 9:26 tells us that the Messiah would be "cut off" that is put to death after the 62 weeks (there were 7 weeks or 49 years which it took to completely rebuild Jerusalem and then another 62 weeks of years which total 483 years.)
Verse 27 tells us that during the 70th week of years (the period between 29 C. E. and 36 C. E.) the Messiah would cause gift offerings to cease at the half of the week, that is 3 1/2 years in. On Nisan 14, 33 C. E. Jesus Christ was impaled on a torture stake and put to death, at that very instant the curtain separating the Holy from the Most Holy in the temple was rent in two:
"“And he will keep the covenant in force for the many for one week; and at the half of the week, he will cause sacrifice and gift offering to cease."-Daniel 9:27.
"And look! the curtain of the sanctuary was torn in two, from top to bottom, and the earth quaked, and the rocks were split."-Matthew 27:51.
This was symbolic of the fact that not only had Jesus fulfilled the law and done away with it, but also the Most Holy with its shekinah light representing Jehovah's presence had been transferred from the typical representation in the temple to heaven itself.
Now that we have the exact date from Daniel's prophecy of when Messiah was to be "cut off" that is put to death, what other further detail does Jehovah reveal about the city and its temple? This:
"“And the people of a leader who is coming will destroy the city and the holy place. And its end will be by the flood. And until the end there will be war; what is decided upon is desolations."-Daniel 9:26.
Here Daniel was told that "the people of a leader" that is the Roman armies would come and destroy the city and the holy place. Why? "And until the end there will be war; what is decided upon is desolations."-Daniel 9:26.
Daniel already foretold that what had already been decided upon for Jerusalem and its city was destruction and it is in the prophecy along with when the Messiah would be put to death. So Jehovah had already foreseen the Jewish race as a whole as rejecting the Messiah and putting him to death. Because of that Jehovah would have Jerusalem and its temple destroyed. And that took place just as was foretold.
Now what exactly would have been the outcome if the Jewish race did not reject the Messiah and put him to death? Jehovah never even gives the idea a thought as he already foretold what was going to happen many centuries before it did. But initially Jehovah did promise the nation of Israel that if they kept the covenant they made with him at Mount Sinai that they would become to him a kingdom of priests:
"Now if you will strictly obey my voice and keep my covenant, you will certainly become my special property out of all peoples, for the whole earth belongs to me. You will become to me a kingdom of priests and a holy nation.’ These are the words that you are to say to the Israelites.”-Exodus 19:5-6.
Since the Jews as a nation rejected the Messiah and put him to death as Jehovah foretold they would do they were rejected as a people and did not enter into the New Covenant for a kingdom of priests. (In the Law Covenant only the tribe of Levi had the preisthood, they were not a nation of priests). Jesus Christ would have been their high priest.
But now Jesus Christ is the high priest of the Christian congregation made up of originally Jews, but very few. Most are people of the nations and to them Peter, a Jew, and apostle of Jesus Christ was inspired by Jehovah God to write:
"But you are “a chosen race, a royal priesthood, a holy nation, a people for special possession, that you should declare abroad the excellencies” of the One who called you out of darkness into his wonderful light. For you were once not a people, but now you are God’s people; once you had not been shown mercy, but now you have received mercy."-1 Peter 2:9-10.
So the promise for a kingdom of priests was given to the anointed Christian congregation. All those called and chosen by God will go to heaven and reign with Jesus Christ in his kingdom over the earth, both as kings, and as priests:
(Revelation 5:10) and you made them to be a kingdom and priests to our God, and they are to rule as kings over the earth.”
(Revelation 20:6) Happy and holy is anyone having part in the first resurrection; over these the second death has no authority, but they will be priests of God and of the Christ, and they will rule as kings with him for the 1,000 years.
This promise was given to the anointed Christian congregation because the Jews lacked faith and put the Messiah to death. We could speculate on how it would have been different if they were obedient to the word because the promise was going to be given to them. But it is pointless. Jehovah God in the Hebrew scriptures didn't even hold out the thought. He promised that he would give the covenant to people other than the Jews long before Messiah came to earth and was put to death by them:
"They have incited me to fury with what is not a god;
They have offended me with their worthless idols.
So I will incite them to jealousy with what is not a people;
I will offend them with a foolish nation."
-Deuteronomy 32:21.
That prophecy was made way back in Moses' day. So at the very beginning Jehovah already foretold the outcome for the Jewish race.
(Hosea 2:23) I will sow her like seed for myself in the earth, And I will show mercy to her who was not shown mercy; I will say to those not my people: “You are my people,” And they will say: “You are my God.”’”
(Romans 9:25) It is as he says also in Ho·seʹa: “Those not my people I will call ‘my people,’ and her who was not loved, ‘beloved’;
(Romans 11:11) So I ask, They did not stumble and fall completely, did they? Certainly not! But by their false step, there is salvation to people of the nations, to incite them to jealousy.
(1 Peter 2:10) For you were once not a people, but now you are God’s people; once you had not been shown mercy, but now you have received mercy.