The apostles and elders met to consider this question.
It is not the entire church who decides or keeps doctrine. Doctrine is handled by the elders of the church; this is a consistent principle throughout the New Testament, and borrows from the synagogue model.
As Protestants, we more than anyone else believe that each individual should be in daily Bible study and that the Holy Spirit can lead them to insights. But…we Protestants also must hold and recognize that in the Bible itself, it is not taught that all men or women can be experts in difficult points. It is easy for a child to read the Scriptures and understand the basic ‘big picture’ story; and it is fairly easy for any believer to gain wisdom and insight from it. But difficult theological questions require a great deal of study and reflection; indeed, no one person can do it. That is why we have a plurality of elders who meet and study the teachings of the apostles at a much deeper level so that we may help serve in the role of shepherding the church to be more Christlike. It is the primary role of Elders to do so, and there has been someone serving this role since the very beginning of Israel—ever since judges were assigned by Moses and then leading into the priesthood and, eventually, the elders of synagogues and churches.
Now we as Protestants do not hold—as do Catholics or the Orthodox—that one group of Elders claims authority over any other in their interpretation of Scripture. Rather, we hold that any plurality of Elders who meet the qualifications (which is a key point) and who meet together praying and reflecting on Scripture together can discern God’s purposes and meanings and give wise counsel to make you more like Jesus. Not infallible counsel, but wise counsel.
After much discussion, Peter got up and addressed them: ‘Brothers, you know that some time ago God made a choice among you that the Gentiles might hear from my lips the message of the Gospel and believe.’
Peter was first called to go preach to the Gentiles in about 37 AD. About 11 years later, Paul was called on his first missionary journey and the explosion of Gentile believers happened.
So Peter started the Gentile conversions about a decade before, but it was still a small and rare thing. Not many Gentiles had been converted, and so the debate really was not a very important one in the church.
But then Paul (having been a believer and disciple for 14 years at this point) was called into the mission field and became a missionary. He began preaching to the Gentiles and within a year, there were Gentiles being converted by the thousands. His ministry was having major fruits, the biggest explosion of new believers since Pentecost.
What had previously been a minor debate when Peter was preaching on the “wrong side of the tracks” was now seen as a major threat to the church. Those who had opposed Peter 11 years ago in Acts 11 were now furious and making such an impact.
God, who knows the heart, showed that He accepted them by giving the Holy Spirit to them, just as He did to us.
The appearance of the Holy Spirit in the conversion of the Gentiles was direct evidence that God did not see a difference between Jews and Gentiles.
The primary reason that such miracles occurred was not to indicate that miracles would routinely occur during conversions, as some denominations have tried to make it; this passage clearly states that the Holy Spirit’s miracles occurred during these conversions as proof positive that God had blessed and approved them.