I advise you, when you hear a gospel sermon, and it is not in all respects to your satisfaction, be not too hasty to lay the whole blame upon the preacher. The Lord’s ministers have not much to say in their own behalf. They feel (it is to be hoped) their own weakness and defects, and greatness and difficulty of their work. They are conscious that their warmest endeavours to proclaim the Saviour’s glory are too cold; and their most importunate addresses to the consciences of men are too faint; and sometimes they are burdened with such discouragements, that even their enemies would pity them if they knew their case. Indeed they have much to be ashamed of; but it will be more useful for you, who are a hearer, to consider whether the fault may not possibly by in yourself.
Perhaps you thought too highly of the man, and expected too much from him; or perhaps you thought too meanly of him, and expected too little. In the former case, the Lord justly disappointed you; in the latter, you received according to your faith. Perhaps you neglected to pray for him; and then, though he might be useful to others, it is not at all strange that he was not so to you. Or possibly you have indulged a trifling spirit, and brought a dearth and deadness upon your own soul; for which you had not been duly humbled, and the Lord chose that time to rebuke you.
— John Newton, Works (Banner of Truth, 2015) 1.153