Paul sends a special note to tell Archippus to make sure he fulfills the ministry to which he has been called (Colossians 4:17). I wonder why he thought it necessary to write this? Was the man discouraged? Was he procrastinating moving into the place of leadership God had opened up for him? Was he delaying out of fear for his life or was it self doubt?
We have no way of knowing what was happening in Archippus' life. But the instruction holds true for all readers. Be sure to do the task God has given you to do.
You are right if you fear you can't do it well enough. No one can. That is why we depend on God to work through us. To not do it is to say God is incapable of using you for his glory. Do you really want to say that to or about God?
