Here again Paul shifts the subject a little bit. The word translated ‘despise’ in the Greek literally means disesteem, look down on him, pull him down, be critical of him.
That is our duty. This is not saying that Christian workers, however poor they may be at their jobs, must never be criticised and always respected. But it's saying, insofar as they're working their hearts out for the Lord, you must get alongside them, and value and appreciate them, and support them and help them. When Satan whispers in your ear, ‘This fellow is beneath us’, banish the thought, and conduct him fourth in oneness and peace.