What was the relationship between Paul and John the Apostle?
In Jerusalem, James, Peter, and John were reputed to be pillars. The three gave their right hands to Paul and Barnabas as a sign of partnership. Galatians 2:9
What the Bible says
Galatians 2:9
And when they had known the grace that was given to me, James and Cephas and John, who seemed to be pillars, gave to me and Barnabas the right hands of fellowship: that we should go unto the Gentiles, and they unto the circumcision:
Douay-Rheims Bible (Challoner revision), public domain.
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Meet Paul and John the Apostle.