Paul and Barnabas had traveled together for two years.  Paul suggested to Barnabas…it was time to return to the different churches that had been established during the first missionary journey.  He was interested in seeing how the new believers were doing.
(Acts 15:36)

Barnabas said “yes” and he would like to include John Mark.  (Acts 15:37) Uh-oh.  John Mark had not stayed the course…in fact he left that first missionary outreach fairly soon.  (Acts 13:13)

Paul adamantly refused because John Mark had deserted them and returned home.  Paul’s past experience warned him not to do that again.
There was such a sharp disagreement between Paul and Barnabas that they separated from each other.
Barnabas took John Mark and sailed to Cyprus.
Paul chose Silas and went on the second missionary journey.  The believers in Antioch committed them to the grace of the Lord – (the favor and mercy of the Lord).  (Acts 15:39-40)

Sharp disagreements separate and divide good friends.

Past experience determines present decisions with far-reaching results.

We can know from another letter Paul wrote years later that he desired reconciliation with John Mark.  Paul wanted him to be with him for Mark had become a valuable part of the ministry.

Did you notice?  The Scriptures do not condemn Barnabas and John Mark or Paul!  Scripture gives the facts and then moves on…

Where did Paul and Silas go?
(NASB) Acts 15:41 “And he was traveling through Syria and Cilicia, strengthening the churches.”

What should you and I remember when we become upset, angry with fellow believers?  We should remember what Paul learned from this experience.  In the letter to the Philippians, Paul wrote:
(NASB) Philippians 3:13-14 “Brethren, I do not regard myself as having laid hold of it yet; but one thing I do: forgetting what lies behind and reaching forward to what lies ahead,
14 I press on toward the goal for the prize of the upward call of God in Christ Jesus.”

Forgive, forget the past and press forward into the future.