Actually, it isn't that sin has evolved. I tend to think of Satan as a "one trick pony," with just a really good trick: lies. But, according to a very interesting sounding book simply called Sin: A History, the metaphors and imagery humans who have entered into a relationship with God use to describe our experience of having sinned against him has changed over the millenia, and this change is captured in the language of the Old and New Testaments.
The author is Gary Anderson, a professor of Old Testament and Hebrew Bible in the department of theology at the University of Notre Dame. He gave an interview with Christianity Today that can be found in its entirety here. I suppose like a lot of new ideas about the scripture, Anderson's discovery had the feel of an epiphany (a manifestation, or, perhaps, a revelation).
I was reading a Qumran text called the Damascus Covenant, and I noticed several instances in which the scroll described forgiveness of sins using a Hebrew verb that in the Hebrew Bible never has that meaning. The scroll used the verb 'azab, which generally means "to forsake." It struck me as quite odd.
While there are a variety of metaphors used for sin in the Scriptures, in the Old Testament the most common metaphor is "burden," or "weight." For example, in Psalm 65, we read, "To you all flesh will come with its burden of sin. Too heavy for us, our offenses, but you wipe them away." Isaiah foretells the Suffering Servant of God as one "pierced for our offenses, crushed for our sins." (Is 53:5)
As I pondered it, I realized that the Aramaic verb for "forgiven" means exactly that. It means "forsake" in the literal sense, because in Aramaic to forgive a sin is to remit what you have coming to you in the sense of a debt. You're forsaking an obligation. Someone who holds a debt over someone else technically can collect that debt whenever he wishes. And if by dint of merciful circumstance he decides not to collect, he forsakes or abandons that right.
For me this was an epiphany. What we're witnessing in that little Qumran text is a new way of thinking about sin and forgiveness. It's not found anywhere in the Old Testament, but, strikingly enough, it becomes quite common in the New.
Interestingly, if you Google "sin," "forgiveness," "burden," "weight" you won't get many helpful hits. That is because ordinarily that common metaphor of forgiveness as a release from a burden is translated simply as "forgiveness of sin." That's the difficulty of translating a metaphor or image into a concept that we think everyone understands. It can lose a bit of it's visceral power. In addition, it can mask the development of a different way of seeing something or expressing an experience.
Anderson describes a surprising discovery he made about how Jews came to think of sin. Jesus doesn't use the image of sin as a weight or burden, he claims.
...the complete absence of this metaphor is particularly striking in the teaching and parables of Jesus. He never talks about sinful individuals bearing enormous weights on their shoulders, as you might have expected from the Old Testament. Instead, he talks about debtors and creditors and building up treasures in heaven. None of those images can be found in the Old Testament proper, especially for the First Temple period. But they're common in Second Temple Hebrew and Aramaic, and it's no surprise that this becomes the predominant way for Jesus to speak about sin.
I am not a scripture scholar, but it seems to me that Jesus might, at one point, use the "old" image of sin as weight. In Matthew 23:2-4, Jesus tells the crowd and his disciples, "The scribes and the Pharisees have taken their seat on the chair of Moses. Therefore, do and observe all things whatsoever they tell you, but do not follow their example. For they preach but they do not practice. They tie up heavy burdens (hard to carry) and lay them on people's shoulders, but they will not lift a finger to move them." The burden here seems to be the law as expounded by the scribes and Pharisees, which St. Paul observed could only help us recognize our sin, but not overcome it: "no human being will be justified in his sight by observing the law; for through the law comes consciousness of sin." (Rom 3:20)
If this burden were an awareness of sin, then the scribes' and Pharisees' unwillingness to "lift a finger" to remove the burden may very well point to their unwillingness to forgive, or even admit God's willingness to forgive. Such a situation would make sin indeed to seem like a crushing load.
But as sin begins to be seen as a debt, a surprising correlative emerges.
...once the Second Temple period Jewish writers and Christian writers began to think of sin as a debt, this led immediately to the correlative idea that meritorious actions, virtuous actions, create a credit.
I would suggest that the greatest credit we can "earn" from God is that same credit which the patriarch Abram was given by God. "Abram put his faith in the LORD, who credited it to him as an act of righteousness." (Gen 15:6) This leads to the interesting situation in which we are given credit by God for something which we have already received from Him!
Here the work of George Lakoff and Mark Johnson on the logic of conceptual metaphors is very important. If sin is a debt, that means we owe money. And if virtuous activity is going to be a credit, well, the most obvious way to accumulate credits is by giving away money—hence almsgiving. Within synagogue and church, it's true that one can gather merits by any act of charity. Matthew 25 is a classic instance of that, of clothing the naked, feeding the poor, visiting the sick, and so on. But pride of place in this period is reserved for actually giving away your coins and funding what Jesus calls a treasury in heaven.
St. Ephrem, a fourth century poet and theologian observed this in a poem when he wrote, "The enricher of all borrows from all." Anderson comments on this image,
Almsgiving was construed in the divine economy as an act of making a loan to God. It was very early on tied to Proverbs 19:17: "He who is kind to the poor lends to the Lord, and he will reward him for what he has done."
Jesus tells us quite clearly that not all almsgiving leads to an addition in a heavenly account with our name on it. On Ash Wednesday we were told,
And then, Ephrem says, in the New Testament, God ... presents himself as a poor person desiring your money, but he himself, we know, is not poor at all. He's the enricher of all. He, in fact, provides us with the very gifts that we are going to return to him. Giving money to the poor is part of what God has ontologically made the very structure of the universe. That is, the universe operates by a principle of charity. That God loves the world. That God loves the poor. We're to love the world and love the poor, and if we do such we will benefit from acting in a way in which God himself acts.
take care not to perform righteous deeds in order that people may see them; otherwise, you will have no recompense from your heavenly Father. When you give alms, do not blow a trumpet before you, as the hypocrites do in the synagogues and in the streets to win the praise of others. Amen, I say to you, they have received their reward. But when you give alms, do not let your left hand know what your right is doing, so that your almsgiving may be secret. And your Father who sees in secret will repay you. (Mt 6:1-4)
The almsgiving of a hypocrite is null because they seek the attention and admiration of others, and that is their reward. The problem apparently is they are, as the name suggests, "stage actors," "pretenders." Almsgiving is meant to be an act of love (charity); of genuine concern for the well-being of another. In such a case it is an act in imitation of God. The hypocrite is playing the part of someone who desires the good of another, but in reality they simply want human praise. And, Jesus, says, that is the only reward they will receive.
Both images for sin are powerful and help us understand the importance of forgiveness. Many times in confession I have had people tell me they feel as though a weight has been removed. Colloquially we'll even say, "I had to get that off my chest," after we've made a confession of some kind, or "shared a burden." We have the power to free others from heavy loads of guilt. Often, it may require us to say, "I'm sorry," first. Because, let's face it, often the pain inflicted by sin goes both ways. We have to be willing to live without our own burdens, along with the sad pleasure of feeling wronged. Moreover, to be unwilling to forgive may very well put us in the same camp as the Pharisees who wouldn't lift a finger to relieve the burden - i.e., forgive - those who were unable to keep the Law.
When it comes to thinking of sin as a debt, Jesus makes it clear that our Father is willing to write off the huge, unpayable debt we owe Him because of our choices to do our own will, rather than His which is born of his infinite love for us. Whether it's the story of the Prodigal Son, or the parable of the servant whose huge debt is written off by his master, forgiveness is freely given those who ask for it. And, in the story of the servant, the implication is that we, too, should forgive the debts of others in imitation of God in Whose image and likeness we were made. So to "write off debts" or "relieve heavy burdens" is to really become more fully human and more like God.