Once Paul was accepted as a sincere brother in the Lord by the Apostles at Jerusalem (Acts 9:27), this didn’t mean that Paul’s Gospel was fully embraced by the church authorities there. We receive a glimpse of Peter’s uneasiness with Paul’s understanding in Acts 10 when Peter actually needed a special vision from the Lord to change his point of view. James, the Lord’s brother and later apparent head of the Jerusalem church, didn’t make any official decision on Paul’s Gospel until Acts 15, a little over a decade after Paul’s first visit to Jerusalem. Nevertheless, an unwritten agreement between Paul and the leaders of the Jerusalem church seems to have been ironed out in the 15 days Paul spent with Peter (Galatians 1:18), during which time, he also seemed to have met with James, the Lord’s brother (Galatians 1:19).
Many advances seem to occur during times of trouble. Consider for example the leap forward in medicine during times of war like World War II in the 20th century CE. Moreover, science really benefited when U. S. politicians wanted to get to the moon before the communists during the so-called cold war of the latter half of the 20th century. I don’t believe it was any different during the stressful times of the persecution of the early church. Sure, everyone wasn’t persecuted, but all were on notice and under the suspicious eye of the Temple authorities at Jerusalem. These were times of need to understand rightly. Brethren were beaten, exiled and murdered, all with the approval of Jewish politics. The Apostles and other leaders of the Jerusalem church were not simply twiddling their thumbs, while hoping the persecution wouldn’t spread to them. They were praying, studying and meditating on the word of God, and probably filing official complaints against the Temple authorities to the Roman government, when the president of Syria came to Jerusalem on occasion.
Jesus’ appearance to Paul while on the road to Damascus, and Paul’s subsequent labor in the Scriptures in Arabia to gain the needed revelations from God, enabling him to reach out to save the gentiles, represents a great leap forward in the Gospel movement across the Empire. Nevertheless, who fully understood the hand of God in it all during Paul’s first visit to Jerusalem following his conversion (Galatians 1:15-18)? Did anyone, including Paul, understand how important his mission would be to western civilization in the centuries to come? I agree with Christian theologian, August Neander, that “God reveals himself in his word, as well as in his works… it is a law of revelation that the heart of man should be tested in receiving it, and that in spiritual life, as well as in the bodily, man must eat his bread in the sweat of his brow.” It doesn’t always come to us easily. Misunderstanding among brethren often abounds. Consider, for example, the great many Christian denominations we have today, all because we cannot simply agree that brethren can worship together and still disagree about some things.
The first century church understood this. In fact, Judaism was splintered up into many factions, and the Temple authorities considered Jesus’ disciples just another sect in Judaism. Peter addressed this same problem in Acts 6 when the Hellenist Jewish believers had differences of opinion. Peter, representing the leadership at Jerusalem, agreed that they should worship apart from the Palestinian believers. As a result the church grew. Paul’s 15 days in Jerusalem was similar to what occurred in Acts 6. Some type of understanding, an unwritten agreement if you will, was reached between Paul and the Jerusalem church leaders. The difference between it and what denominational Christianity means today is that Stephen and company and Paul and company recognized the official leadership of the Jerusalem church. That is, there was never a complete break within the church, only different traditions of following Jesus. It was all one church that recognized the importance of its birthplace—Jerusalem.
 Cited by John Haley in his book Alleged Discrepancies of the Bible; Chapter 1, page 15. Also compare Genesis 3:19