Oxford defines sin as “an immoral act considered to be a transgression against divine law.” There are two concepts here: that of immorality, and that of breaking God's law. Merriam-Webster gives these as two separate meanings: “1. an offense against religious or moral law,” and “2. transgression of the law of God.”
Both concepts, it seems to me, are necessary for a full appreciation of the nature of sin. “Transgression of the law of God” or “transgression against divine law,” on its own, leaves the impression that God's law might be capricious or arbitrary. If God declared murder a good thing, and charity a bad thing, would they become so? They would not. Morality exists as an absolute apart from God's willing it. God cannot will evil to be good.
Were this not so, it would be meaningless to say that “God is good.” not that God is subject to the good, but rather that he is morally good in his essential nature. “He cannot deny himself” (2 Timothy 2:13). Therefore, to sin is not only to offend against God, but to offend against morality as an objective quality, against objective right and wrong. In the words of the Catechism of the Catholic Church, “Sin is an offense against reason, truth, and right conscience; it is failure in genuine love....” (CCC 1849).
However, true morality also necessarily involves an obligation to love and obey God, to keep God's laws. When Jesus summarizes morality in two commandments, “Love God,” and “love your neighbour as yourself,” he gives the former the priority. Similarly, the first three (or four, depending on your numbering system) of the Ten Commandments presume a moral obligation to honour God.
If one accepts the definition of God as absolute being, and absolute perfection, it follows that he is also absolute goodness. Aquinas states this as a matter of definition: “the word 'God' means that He is infinite goodness” (Summa 1:25). Or, in the words of the Gospel, “None is good but God alone” (Luke 18:19) – to say “good” is to say “God.” If one does not believe in, and revere, absolute goodness, this in itself is a turning away from the good. If an atheist genuinely holds that there is no such thing as moral good, he is not in the end a moral being. If he holds that there is such a thing as moral good, he is not really an atheist. He is simply not calling God by the word “God.”
Given that we truly believe in the absolute moral good, why do we ever do evil? Why does sin enter our lives? Why are we tempted?
The classic explanation, of course, is the story of the Fall of Man. According to Genesis 3:6, Eve faced three temptations leading her to commit the original sin: “So when the woman saw that the tree was good for food [1], and that it was a delight to the eyes [2], and that the tree was to be desired to make one wise [3]...” (RSV).
The first temptation seems clear enough: our sensual appetites, though in themselves good, may conflict with a higher good.
The second temptation is less clear. Firstly, if it is simply a matter of the apple being pleasant to look at, this is not a separate temptation from the first. Moreover, if this sensual pleasure of seeing the apple is what is desired, eating the apple is not the way to acheive it: this removes the apple from sight, and therefore ends this sensual pleasure. Conversely, leaving the apple on the tree in obedience to divine command is the best way to satisfy this desire.
Accordingly, the second temptation must be something else: a desire to show the apple to Adam. She would have something that Adam did not. The second temptation is the temptation to “look good” to others; to win their esteem. While good in itself, this too can conflict with the ultimate good, as appearance can conflict with reality.
The desire for wisdom is explained further in the passage: knowledge of good and evil is promised to make Eve “like God.” This is the sin of egotism or spiritual pride.
There also seem to be three temptations, and three stages of the Fall, in Genesis. Eve’s temptation is only the first: on the literal, most basis level, to eat the fruit—temptation of the senses or the flesh. Then Adam too is tempted, and eats—tempted by his wife, the first historic instance of peer pressure. He must keep up with the Joneses. With this, significantly, comes shame, social guilt. Then comes the next temptation: Cain’s murder of Abel. He does this out of spiritual pride: resentment that God seems to favour Abel.
Temptations, it seems, always come in threes; and, I submit, this same set of three. Both Luke and Matthew, for example, tell of Jesus facing three temptations in the wilderness: turn stones to bread, rule the world, jump from the temple roof. These are Eve's three temptations, again, in order; which Jesus, however, resists. The Book of Common Prayer, following Peter Abelard, cites “the world, the flesh, and the devil” (Abelard, Exposition of the Lord's Prayer): the same three, but in a different order, 2, 1, 3. 1 John 2:16 also seems to have our list of three: “For all that is in the world, the lust of the flesh and the lust of the eyes and the boastful pride of life, is not from the Father, but is from the world.” Lust of the flesh, lust of the eye, and pride: 1, 2, 3.
I order the three temptations in the way suggested by the historical sequence in the Bible. The same sequence is also given by Luke and John—by a majority of our sources. Matthew and the Book of Common Prayer have different sequences, but also do not agree between themselves: 1, 3, 2 and 2, 1, 3, respectively.
Why are the temptations of the flesh the first temptations? Probably, because the pleasures of the flesh are the lowest common denominator, something even young children or animals feel strongly. Our instinctive, animal desire is for material or physical comfort and the absence of pain; things like wanting to eat, seeking warmth, getting a good sleep. The complete surrender to this temptation is the comprehensive sin of materialism, of living “by bread alone.” Wealth too is, at base, a desire of the flesh, because the essence of wealth is material possession. Hence the proverb “the love of money is a root of all kinds of evil” (1 Timothy 6:10).
The second temptation, for social appearances or social standing, is referred to by the Book of Common Prayer as “the world”-- as in Merriam-Webster’s second definition: “All of the people, societies, and institutions on the earth.” “Peer pressure,” we would say, with teenagers; as the French would say, “tout le monde.” Similarly, “lust of the eye” in 1 John does not mean a desire to own things you see—that again would be only a duplicate of lust of the flesh, less clearly described. It refers to a desire to be looked at, or “looked up to.”
Finally, the sin of pride—the devil’s sin, hence by synecdoche referred to in the Book of Common Prayer as “the devil.” This is “putting God to the test,” putting oneself above God in some sense. This was the last temptation of Job, the righteous man, a conviction of his own righteousness and that God owed him something in terms of treatment. “Shall he that contends with the Almighty instruct him?” (Job 40:2).
It would seem that each temptation in turn leads to a deeper level of evil. A simple lust for the flesh, as of a Falstaff, is in the end rather forgivable. There is relatively little of malice in it. People who avoid the allure of materialism, then succumb to the allure of social pomp or worldly power, seem more purely evil: Hitler or Park Chung Hee were both seemingly personally incorruptible. No doubt it is for this reason that Jesus and the Gospel save their greater wrath not for women taken in adultery, but for the scribes and Pharisees.
And the sin of spiritual pride, finally, is, as noted, the sin of the Devil himself.