The Bible doesn't cover up the fact that Paul and Barnabas had a sharp disagreement over whether to take John-Mark on their 2nd missionary trip. Unable to resolve their differences they parted company from this point on. There are still sometimes quite strong disagreements between Church Leaders today. This is not the plan, not the intention, yet equally God is not phased by it. We need to learn how to disagree well, not let differences fester into resentment, not seek to destroy or disrupt another leader's work, and look for opportunity for reconciliation and harmony, noting that many years later Paul writes to Timothy that John-Mark is helpful in his ministry.