The angel said to Mary: Luke 1:32 He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David. 33 And he shall reign over the house of Jacob forever; and of his kingdom there shall be no end. 34Then said Mary unto the angel, How shall this be, seeing I know not a man? 35And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
And then Jesus turned it down here:
John 18:36 "Jesus answered, “My kingdom is not of this world. If My kingdom were of this world, My servants would fight, so that I should not be delivered to the Jews; but now My kingdom is not from here.”"
John 6:15 When Jesus therefore perceived that they would come and take him by force, to make him a king, he departed again into a mountain himself alone.

The angel did not say to Mary this was a spiritual kingdom so this topic is not for those that just jump from pillar to post quoting from different Gospels just to try and make up an answer they don't know.

Now if Jesus is the final Messiah then how could the Bible have got this wrong as Jesus has stated that "My kingdom is not of this world" whereas the prophecy is that The Lord God shall give unto him the throne of his father David.

So Jesus might have come to prepare the way for a final Messiah who will be given the "throne of his father David, And he shall reign over the house of Jacob forever; and of his kingdom there shall be no end"