As soon as a man lets his work become a matter of mere form or routine, it sinks into a performance in which the preacher is simply an actor. He is only acting a part, as he might in a play at the theatre; and not speaking from his inmost soul, as a man sent from God. I do beseech you, brethren, speak from your hearts, or else do not speak at all. If you can be silent, be silent; but if you must speak for God, be thoroughly sincere about it. It would be better for you to go back to business, and weigh butter or sell reels of cotton, or do anything rather than pretend to be ministers of the gospel unless God has called you to the work. I believe that the most damnable thing a man can do is to preach the gospel merely as an actor, and to turn the worship of God into a kind of theatrical performance. Such a caricature is more worthy of the devil than of God. Divine truth is far too precious to be made the subject of such a mockery. You may depend upon it that, when the people once suspect that you are insincere, they will never listen to you except with disgust, and they will not be at all likely to believe your message if you give them cause to think that you do not believe it yourselves.
Spurgeon, Charles H (2012-03-27). The Soul Winner (Kindle Locations 688-696). Counted Faithful. Kindle Edition.