Children have to scuffle in order to grow up normally. Each individual must develop his own conscience, and allowances must be made for different personalities. In the final analysis there are situations which may arise that can only be solved by a separation. But separation per se is not sinful. Some have said that when two disagree, both may be wrong, but both cannot be right.
Someone has to be wrong if there is a disagreement.
It is interesting to note that both Paul and Barnabas were right even though they disagreed. Barnabas had the good of Mark in view, while Paul had the good of the work in view, but if either or both had been wrong, it would not have been fatal to their salvation. Their disagreement made it imperative that they go into different fields, but they were still brethren who could sing, pray and worship together. They remained brethren and they treated one another as brethren. Each has his own field of work and will reach some who otherwise would never hear the gospel.