1 Corinthians 2:4

"And my speech and my preaching was not in persuasive words of wisdom:" that is, had not the wisdom from without. Now if the doctrine preached had nothing subtle, and they that were called were unlearned, and he that preached was of the same description, and thereto was added persecution, and trembling and fear; tell me, how did they overcome without Divine power? And this is why, having said, "My speech and my preaching was not in persuasive words of wisdom," he added, "but in demonstration of the Spirit and of power." Dost thou perceive how "the foolishness of God is wiser than men, and the weakness stronger?" They for their part, being unlearned and preaching such a Gospel, in their chains and persecution overcame their persecutors. Whereby? was it not by their furnishing that evidence which is of the Spirit? For this indeed is confessed demonstration. For who, tell me, after he had seen dead men rising to life and devils cast out, could have helped admitting it? But seeing that there are also deceiving wonders, such as those of sorcerers, he removes this suspicion also. For he said not simply "of power," but first, "of the Spirit," and then, "of power:" signifying that the things done were spiritual. It is no disparagement, therefore, that the Gospel was not declared by means of wisdom; rather it is a very great ornament. For this, it will be allowed, is the clearest token of its being divine and having its roots from above, out of the heavens.