Why can't I judge another person's servant?
You cannot judge another person's servant because that servant belongs to God, not to you. You are not his boss, you do not pay his wages, and he is not your employee. God has received him and God alone is his judge, so you have no authority over him.
Les explains that Paul uses an everyday example: if someone is another man's servant, you are not his boss, you are not paying his wages, and he is not your employee, so judging him does no good. In the same way, believers belong to God, who has received them and is their only judge. Les points back to Romans 8, where no one can judge us because the one who died for us is the judge. Therefore, when other believers do not live as you think they should, you are in no position to judge them; you may point them to Scripture, but Paul absolutely rejects judging another person, because God is the boss.
Who art thou that judgest another man’s servant? to his own master he standeth or falleth. Yea, he shall be holden up: for God is able to make him stand.