Initially, the serpent had legs and could even stand upright according to some of the Patristic writers, but God cursed this serpent to crawl after the incident in the Garden happened. On an allegorical dimension, the serpent symbolizes sensual pleasures. And, as St. Ambrose taught, those who live for the pleasures "of the stomach" are said to "walk on their bellies," and that is what the curse on the serpent embodies on one level. In Phillipians 3:19, St. Paul is addressing the issue of those who are as he calls "enemies of the Cross," and one thing he says about such people is that "their god is their belly, and their glory is their shame," because as he continues, "they set their minds on earthly things." The ultimate "enemy of the Cross" is Satan, and in essence what the Apostle is talking about here is the sin of gluttony. Gluttony, it must be noted, is not just about engorging oneself with food, as one can have a gluttonous appetite for anything - power, money, sex, etc. Gluttony is a form of idolatry in itself, in that a person's life is consumed and devoted to whatever the object of the gluttony is. This is the very sin Satan deceived Eve into indulging, because she gained a gluttonous desire for a fruit she might otherwise had not paid attention to. Gluttony is however the product of coveting, which the Ten Commandments in Exodus 22:17 specifically says is forbidden as a "Thou shalt not." Coveting something leads to a gluttonous desire, and thus culminates in the commission of another sin that is forbidden by the Decalogue - stealing. This is why it is important to understand that sin is interconnected, as one sin is related to others, and at the root of them all is the sin of pride. That is why, in the New Testament, Jesus puts all sin on equal footing, as the commission of one type of sin is the same as committing any type of sin. As the devil is a tempter and agitator of sin himself, the curse against the serpent again is not against all snakes, but rather is directed against Satan himself. As Satan didn't have the ability, due to his own corrupt nature, to confess sin, he had no ground to excuse himself and therefore this may attribute to his silence when God confronts him - this is something St. Augustine also would expound upon in his writings. Satan's punishment, therefore, is that he has in his power those who despise the command of God. He is guilty of the greater punishment in that he revels in this unhappy power. And, when it says later that the cattle are above him, it does not solely refer to nature, but rather in nature's preservation. The chest then is a symbolic image of pride, and the belly one of carnal desire.
It is also worth mentioning that the devil destroys the earthly-minded. As Caesarius of Arles wrote some centuries ago, the devil "consumes" those who are earthly-minded, or those who place their hope in earthly things. So, how does he do this? Any earthly pleasure is temporal, and at times in excess can be harmful. Although God created all of nature, some aspects of it are meant to be partaken of with reasonable enjoyment. When that enjoyment becomes an obsession, the object of the enjoyment then in essence becomes an idol. Therefore, in seeing it this way, the devil doesn't consume them himself, but rather he allows the obsession to consume the people it controls.
As to the literal "crawling" of a snake in relation to this passage, some fellow Young-Earth Creationists often cite the boa constrictor, noting that this particular snake has vestigial limbs which they believe is proof for God's curse on the serpent. In reality though, those "vestigial limbs" serve as an aid in reproductive activity, as they are used by the male snake to grip the female snake in the reproductive act, meaning God created the boa constrictor like that. Far from being the remains of "cursed limbs," the vestigial appendages the boa has serve to solely aid in creating more baby boas, that is all. That being said, it is also fascinating that there are no snake fossils in existence either - if the snake "evolved," one would expect to find fossil evidence all over, but it simply isn't there. The reason is that the snake looked different in antiquity to the ones we find today, and perhaps some are looking for the wrong fossil evidence! That is a discussion for a whole other lesson though.
Genesis 3:15 is a clencher for us now, as it bridges God's judgment of the serpent with that of Eve, but it has other significance as well. This passage is often called the Protoevangelium or "First Gospel" because in this dire pronouncement of judgment upon the new humans, there is a sign of hope. Another reference for this passage is "Enmity between the Seeds," and the "seed of the woman" properly understood in this passage is Jesus, but on another level it is also the Virgin Mary. What we see here is an early prophetic insight into a future struggle between a tempter (Satan) and a future redeemer, meaning Jesus, and the struggle ends in triumph for the latter. As Mark Miravalle notes in his book Mary: Coredemptrix, Mediatrix, Advocate (Santa Barbara, CA: Queenship Publishing, 1993) the Virgin Mary was eternally in a complete and absolute opposition to Satan, and would share with her Son in the complete redemptive triumph over Satan (Miravalle, p. 2). That theme bookends the Scriptures too, as we see as well a picture of Genesis 3:15 in Revelation 12. Mary, as a "New Eve," had restored to her what the original Eve lost. So, let us talk about this "seed" a bit.
Over the centuries, the battle of the "two seeds" has been a subject of much discussion, and there are two schools of thought on it. Genesis 3:15 is also understood in light of not only Revelation 12, but also Genesis 6:1-12, and both passages speak of different facets of the same thing. One school of thought on this holds the position that the "seed of the woman" is the righteous descendants of Adam and Eve's son Seth, while the "seed of the serpent" is the descendants of Cain. This view, called the "Sethite view" was originally proposed (but not dogmatically embraced) by Julius Africanus in the 3rd century AD, but today it is held by a number of otherwise orthodox scholars of all Christian traditions, including Fundamentalist theologians like Norman Geisler and John MacArthur as well as conservative Roman Catholic theologians like Scott Hahn. Although held by a number of intelligent and sound scholars of various traditions, this position has a problem in that the Scriptural record does not actually say that all of Cain's descendants were evil and Seth's were good - as we will see in Chapter 4, some of Cain's were actually more righteous than Seth's! Also, both Cain's and Seth's descendants are basically human beings, and God's grace does not distinguish there between them. That leads me to the second school of thought, which I hold to personally and which many others over the years have come to embrace. The second school of thought is based on a reading of Genesis 6:1-12 coupled with what was recorded in early documents such as Enoch, Jasher, and Jubilees, and it was equally held by many early Patristics, including Ss. Jerome, Irenaeus, Justin Martyr, and others. This view states that when a group of fallen angels rebelled with Satan and were cast to earth, they copulated with human women and produced a hybrid species commonly called Nephilim which were large in stature (some up to 36 feet tall). These fallen angels are called the "Watchers" in the ancient texts, and the view that would entail this is known as the "Watchers view." It makes more sense in some aspects to embrace the second view in lieu of the narrative of Scripture as a whole, as it would also explain why God would later order the complete annihilation of certain groups of people whom He deemed condemned. Although we will discuss that more in detail when the study gets to Genesis 6, it is important to mention it here due to the fact it gives an identity of what the "seed of the serpent" is, and the Tradition of the Church upholds this in a profound way as it relates to the Virgin Mary, and we will get to that momentarily. Suffice to say, every Marian doctrine the Church has held (Ever-Virginity, Mother of God, Assumption, and even Immaculate Conception) has the Protoevangelium in Genesis 3:15 at its foundation.
As the "enmity between the seeds" passage relates to the Virgin Mary, there is one specific example which illustrates this beautifully in recent history I want to discuss now. In 1531, an Aztec Indian who was given the Spanish name Juan Diego was walking along a road on his way to Mass in a nearby town near what was the ruins of the ancient temple of an ancient Mesoamerican earth goddess near a place called Tepeyac Hill, just outside Mexico City. As Juan Diego approached the hill, he heard singing, and saw a luminous and beautiful young lady appear before a cloud. This lady, who was the Virgin Mary, gave him a message of hope to his people, who were oppressed, and she assured him that she had heard their cries and would alleviate their sufferings. As proof of this for the bishop, the Lady instructed Juan Diego to take up a bunch of roses which had miraculously appeared into his cloak, and that the bishop (Zummaraga) would see the proof (Warren Carroll, Our Lady of Guadalupe and the Conquest of Darkness. Front Royal, VA: Christendom Press, 1983. p. 100). When he arrived at the bishop's house, he opened his cloak, and the rose petals fell out, revealing this image: