Ante-Nicene Fathers, Vol III:
Tertullian: Part III: The Very Simplicity of God's Means of Working, a Stumbling-Block to the Carnal Mind.

Chapter II.—The Very Simplicity of God’s Means of Working, a Stumbling-Block to the Carnal Mind.

Well, but how great is the force of perversity for so shaking the faith or entirely preventing its reception, that it impugns it on the very principles of which the faith consists! There is absolutely nothing which makes men’s minds more obdurate than the simplicity of the divine works which are visible in the act, when compared with the grandeur which is promised thereto in the effect; so that from the very fact, that with so great simplicity, without pomp, without any considerable novelty of preparation, finally, without expense, a man is dipped in water, and amid the utterance of some few words, is sprinkled, and then rises again, not much (or not at all) the cleaner, the consequent attainment of eternity 8546 is esteemed the more incredible. I am a deceiver if, on the contrary, it is not from their circumstance, and preparation, and expense, that idols’ solemnities or mysteries get their credit and authority built up. Oh, miserable incredulity, which quite deniest to God His own properties, simplicity and power! What then?  Is it not wonderful, too, that death should be washed away by bathing? But it is the more to be believed if the wonderfulness be the reason why it is not believed. For what does it behove divine works to be in their quality, except that they be above all wonder? 8547 We also ourselves wonder, but it is because we believe. Incredulity, on the other hand, wonders, but does not believe: for the simple acts it wonders at, as if they were vain; the grand results, as if they were impossible. And grant that it be just as you think 8548 sufficient to meet each point is the divine declaration which has forerun: “The foolish things of the world hath God elected to confound its wisdom;” 8549 and, “The things very difficult with men are easy with God.” 8550 For if God is wise and powerful (which even they who pass Him by do not deny), it is with good reason that He lays the material causes of His own operation in the p. 670 contraries of wisdom and of power, that is, in foolishness and impossibility; since every virtue receives its cause from those things by which it is called forth.

Footnotes

Consecutio æternitatis.

Admirationem.

i.e. that the simple be vain, and the grand impossible.

1 Cor. i. 27, not quite exactly quoted.

Luke xviii. 27, again inexact.