Acts 15:39 – And the contention was so sharp between them, that they departed asunder one from the other: and so Barnabas took Mark, and sailed unto Cyprus;
Galatians 2:1 – Then fourteen years after I went up again to Jerusalem with Barnabas, and took Titus with me also.
Paul and Barnabas got into a little fight while they were in Antioch once. Unfortunately, it caused them to part ways for many years. They both served the Lord and went on with their Christian lives. They eventually got right with each other many years later when going to Jerusalem.
God still used them both to get the gospel spread. I sometimes think that when someone parts ways with us, we often condemn them to the point of being the devil’s brother. Fortunately, God has a little more mercy than we do. God uses all kinds of people to get his work done. People are just different. They go about things differently, they get them done differently, they like different things, and they like different people. Barnabas saw something in young John Mark that Paul did not. He was mature enough in his Christian faith to give him a second chance. Paul just was not quite there yet.
We as Christians need to give young Christians time to grow. A young Christian can be 70 years old by the way, especially if they have never grown in the Lord. But Christians must grow to make godly decisions. Also, sometimes people go about things different than you. That is okay. Surprisingly, God can still use them. He can use them even when they leave your church and maybe they are a little crossways just like Paul was when he left Barnabas. We are all going to be living together in heaven one day. Try and get along with the brethren as much as you can. Love your brothers and sisters in the Lord and give them the benefit of the doubt like Barnabas did with John Mark. Don’t let contention split you apart in the first place, but if it does, get right about it like Paul and Barnabas. And if you do, do it sooner rather than later.