The answer to that excellent question is provided by God, Himself. In the 3rd book of Exodus, God reveals Himself to Moses: "I am the God of your father, the God of Abraham, the God of Isaac, the God of Jacob.". He then explains that He has heard the plea of the Israelites against their slave drivers and is sending Moses to rescue them. Not surprisingly, Moses, who was tending sheep when this occurred, says: "Who am I that I should go to Pharaoh and lead the Israelites out of Egypt?" Unsure about the whole situation, he asks God: When I go to the Israelites and say to them, 'The God of your fathers has sent me to you,' if they ask me, 'What is his name?' what am I to tell them?" Now we learn His name. God replied: "I am who am." He further qualifies the request by saying: "This is what you shall tell the Israelites: I AM sent me to you."
Notice, He does not say "I was" or "I will be". He refers to Himself as: "I Am" in the present form because God exists, with no beginning or end. While we are finite beings, our souls are immortal and return home to our Creator when we die.
Why did God complicate things by only sending one son, Jesus into this world? Why didn't He send other messengers of His word to all the other civilizations scattered around the globe that were in existence at that time? Why only Israel?
This is another interesting question. He did send other messengers to announce the birth of His Son. History is full of men who have claimed that they came from God, or that they were gods, or that they bore messages from God - Buddha, Mohammed, Confucius, Christ, Lao-tze, and thousands of others, right down to the person who founded a new religion this very day. Each of them has a right to be heard and considered. But as a yardstick external to and outside of whatever is to be measured is needed, so there must be some permanent tests available to all men, all civilizations, and all ages, by which they can decide whether any of these claimants, or all of them, are justified in their claims. These tests are of two kinds: reason and history. Reason, because everyone has it, even those without faith; history, because everyone lives in it and should know something about it.
Reason dictates that if any one of these men actually came from God, the least thing that God could do to support His claim would be to pre-announce His coming. Automobile manufacturers tell their customers when to expect a new model. If God sent anyone from Himself, or if He came Himself with a vitally important message for all men, it would seem reasonable that He would first let men know when His messenger was coming, where He would be born, where He would live, the doctrine He would teach, the enemies He would make, the program He would adopt for the future, and the manner of His death. By the extent to which the messenger conformed with these announcements, one could judge the validity of his claims.
Reason further assures us that if God did not do this, then there would be nothing to prevent any impostor from appearing in history and saying, "I come from God," or "An angel appeared to me in the desert and game me this message." In such cases there would be no objective, historical way of testing the messenger. We would have only his word for it, and of course he could be wrong.
If a visitor came from a foreign country to Washington and said he was a diplomat, the government would ask him for his passport and other documents testifying that he represented a certain government. His papers would have to antedate his coming. If such proofs of identity are asked from delegates of other countries, reason certainly ought to do so with messengers who claim to have come from God. To each claimant reason says, "What record was there before you were born that you were coming?"
With this test one can evaluate the claimants. Socrates had no one to foretell his birth. Buddha had no one to pre-announce him and his message or tell the day when he would sit under the tree. Confucius did not have the name of his mother and his birthplace recorded, nor were they given to men centuries before he arrived so that when he did come, men would know he was a messenger from God. But, with Christ, it was different. Because of the OT prophecies, His coming was not unexpected. There were no predictions about Buddha, Confucius, Lao-tze, Mohammed , or anyone else; but there were predictions about Christ. Others just came and said, "Here I am, believe me". Christ alone stepped out of that line saying, "Search the writings of the Jewish people and the related history of the Babylonians, Persians, and Romans." Even the pagan, Tacitus, speaking for the ancient Romans, says, "People were generally persuaded in the faith of the ancient prophecies, that the East was to prevail, and that from Judea was to come the Master and Ruler of the world." China had the same expectations, as did the Greeks.
The story of every human life begins with birth and ends with death. In the Person of Christ, however, it was His death that was first and His life that was last. It was not so much that His birth cast a shadow on His life and thus led to His death; it was rather that the Cross was first, and cast its shadow back to His birth. His has been the only life in the world that was ever lived backward.
As the flower in the wall tells the poet of nature, and as the atom in the miniature of the solar system, so too, Christ's birth tells the mystery of the cross. He went from the known to the known, from the reason of His coming manifested y His name "Jesus" or "Savior" to the fulfillment of His coming, namely, His death on the cross.
With all due respect, asking someone to read a lengthy religious tract is off-putting. You are not the first to have tried to have me read such a document, and won’t be the last. You have your belief system, and I have mine. I would say though that we have more in common than either of us with an atheist...
That was a very enlightening explanation, thank you for taking the time to do so......