“Do try, as far as you can, to make the very way in which you speak to minister to the great end you have in view. Preach, for instance, as you would plead if you were standing before a judge, and begging for the life of a friend, or as if you were appealing to the Queen herself on behalf of someone very dear to you.
Use such a tone in pleading with sinners as you would use if a gibbet were erected in this room, and you were to be hanged on it unless you could persuade the person in authority to release you. That is the sort of earnestness you need in pleading with men as ambassadors for God.
Try and make every sermon such that the most flippant shall see without any doubt that, if it be an amusement for them to hear you, it is no amusement for you to speak to them, but that you are pleading with them in downright solemn earnest about eternal matters.”
–Charles H. Spurgeon, “Sermons Likely to Win Souls” in The Soul Winner.