Paul, in his letter to the Christians at Galatia wrote these simple, yet very meaningful, remarks:
"Now I say, That the heir, as long as he is a child, differeth nothing from a servant, though he be lord of all; But is under tutors and governors until the time appointed of the father. Even so we, when we were children, were in bondage under the elements of the world: But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law". (Galatians 4:1-4 KJV)
Jesus came to the earth to accomplish certain things, all of which were successfully accomplished in the one thing...the establishment of his church, or kingdom. When Paul wrote the above letter, Jesus had already fulfilled his mission and was reigning over his kingdom from heaven. It has been questioned by many people as to why the Lord waited so long before coming to establish his kingdom.
One only has to look at the predicament in which mankind placed himself, time after time, to see that the time would not have been right for the Lord to attempt to establish his church. Imagine, for instance that he had come at any time before the global flood. Man was unruly from the beginning and grew worse and worse. After the flood and when the populace grew large again, they also grew evil and forsook the Lord. God, through his infinite wisdom and omniscience, could see ahead that the time would have to be when there was relative peace, when His people, the Jews would be held in restraint by a powerful government and would be more inclined towards seeking God's blessings.
God, omniscient, knew from the creation what each peoples would do and His plan for the savior to come to earth was scheduled as all other things concerning the eventual coming of Jesus were. For instance God told Abraham that his seed would eventually become a great nation and would be given the land of Canaan, yet he advised him that it would be to come much later, even after Abraham's death. He explained this to Abraham in Genesis chapter fifteen.
His reason for the postponement of Abraham's seed being allowed to enter any sooner, was that God said the "Amorites iniquity is not yet full," Also his seed, the children of Israel, must be shown that He was indeed their God and realize His strength.
The Roman Empire was young at the time of Jesus birth and was being ruled by Julius Caesar who had taken the name of 'Augustus' which meant 'revered one'. Caesar was the first emperor to rule over the growing empire and has been classified by many historians as the greatest emperor of all those who ruled the empire while it existed. He ruled for approximately forty years, from 27 BC until 14 AD. Until the time of Christ, the Romans had been in almost constant warfare for centuries, gradually taking territories in the Mediterranean basin, which grew them into the empire it became. There is no question that his rule was highly beneficial to the cause of Christ. By the time Octavian took the throne, Caesar had brought about more unity, peace and progress to the area than it had ever realized before.
Although some future rulers in years to come, inflicted considerable persecution upon the Lord's fledgling church, there was limitations to which others could inflict harm upon them. Rome controlled the entire Mediterranean area and therefore, the apostles and the early gospel preachers were free to travel from one country to another with no problem just as we here in the U.S. can cross from one state to another. All were under the same rule.
The Romans also built a network of intersecting roads and other facilities. Some of those roads were actually paved and some are still in use today! Amazing. And these durable roads connected others into every corner of the Empire. Their purpose was that of moving troops and trade, yet they were of considerable benefit to those Christians who were evangelizing the area.
Also, perhaps the one greatest influence for the time Christ's church was to be formed was that some 3 centuries earlier, Alexander the Great had spread the Hellenistic culture with it's Greek language throughout the region and it became the preferred language of the Romans who spoke Latin. This again, was highly beneficial to those who were spreading the gospel of Christ throughout the area.
So, God with His ability to discern future circumstances, was able to know from the beginning, when the fullness of time, the right time, would be for the birth of His Son, Jesus. And the establishment of the Lord's eternal kingdom here on earth.