“Barnabas was determined to take along John, who was called Mark. Paul, however, was not in favor of taking him along with them […]. At this there was a sharp burst of anger, so that they separated from each other.”
All three men involved in the discord were spiritually strong and had an extraordinary record of service to God. (Acts 13:4,5)
Still, there was at least one occasion in which Paul was disappointed by Mark, and eventually, he and Barnabas had a grave argument about it.
In time, though, Mark took on more responsibilities and even wrote a gospel account of Jesus’ life, having been eyewitness to some events. (Mark 14:51,52; Phm. 23,24; 1 Pet. 5:13)
Some time prior to the completion of the gospel, Paul came to forgive Mark and even requested his company in Rome. (2 Tim. 4:11)
This account teaches us that while Christians should constantly strive to display patience and self-control, we are not perfect and from time to time, will have serious disagreements with other mature Christians. (Gal. 5:22,23)
But much like Paul, Barnabas and Mark, such disagreements should not impede our desire to continue serving Jehovah to the best of our abilities. (Acts 15:39b,40)
That a fellow believer has a differing point of view does not automatically disqualify them as a spiritually strong person.