Several important difficulties suggest themselves in the text.
I. The scientific difficulty. The serpent really bears no trace of degradation; its structure is as beautifully adapted to its place in nature as that of the lion or the eagle. Neither can it be said to eat dust: its food consists of the small animals which are its prey.
II. The moral objection. Why was the serpent punished for what he did not do? Shall God visit the craft of the devil on his helpless and unconscious victim?
The answer is, These two objections neutralise each other. If the moralist tells us that God could nothave meant to punish the serpent for what the serpent did not do, the man of science assures us that in fact He did notpunish him. The real severity of the sentence lighted on the real offender, the devil, while the mere form of it was accommodated to the apparent structure and habits of the serpent.
III. If it was the tempter that sinned, why did not the Almighty sentence him openly as the tempter? Because there is a very marked reserve in the Old Testament on the subject of the personal author of evil. The reason of this is obvious: men were not able to bear the knowledge of their great spiritual enemy until their Deliverer was at hand. If we perceive that it was not the will of God at that time to reveal to man the existence of the evil one, we can readily understand why He permitted him to retain his serpent guise.
R. Winterbotham, Sermons and Expositions,p. 8
References: Genesis 3:14; Genesis 3:15. Expositor, 2ndseries, vol. vii., p. 56; Homiletic Quarterly,vol. iii., p. 199. Genesis 3:14-24. J. Cumming, Church before the Flood,pp. 133, 156.