what beautiful discourse i have just read here. this is what i will say on the topic of disagreements and the purpose and results thereof:
in acts 15, paul greatly disagreed w/barnabus about continuing on w/john mark - who fled back home - causing paul and barnabus to part ways in their ministry work. later in col 4, paul tells the colossians should john mark ever present himself to them they are to welcome him as a brother of the [spiritual] circumcision, a fellow worker for the kingdom of God, and that john mark has been a proven comfort to paul.
as taught in prov 27:17, paul sharpened barnabus on partiality but did not discount the usefulness of john mark, only that john mark's lack of maturity in faith had no place in the work paul was embarking on. paul did not say it was wrong for barnabus to continue on w/john mark as his assistant.
in matt 10:38, christ says "he who does not take his cross and follow me is not worthy of me." this is not to say that those who are not spiritually ready are not worthy of God's love and grace. it is a chastisement to teach that we are not to go forward preaching/teaching things we do not yet understand. we are yet babes needing milk unable to handle solid food.
God bless and guide you all in His will.