The word “justified” means that a person has been made right in God’s eyes, from being a sinner to being righteous.
A person born in a Jewish family had a high probability of knowing and worshiping the true God, Yahweh—the Creator of heaven and earth.
The phrase “This issue” is about making believers go back to the Law of Moses to observe it and keep it. See verse 3 and its commentary.
This verse gives us the reason why Paul wanted to go back to Jerusalem to speak with “those recognized as leaders” (verse 2).
Paul received a revelation from the Holy Spirit, but he went to seek confirmation to make sure it was from the Holy Spirit…
After Paul spent considerable time in places like Arabia, Damascus, and other Gentile nations preaching and planting churches, he returned to Jerusalem to speak to the brothers about a revelation he had.
Later on, Paul found out that the saints in Judea, when they heard about Paul’s conversion to Christ, glorified God and rejoiced in what God was doing.