If you read only the Synoptic Gospels for a while, Christianity starts to greatly resemble that dreaded legalism.
For this reason, the kingdom of heaven may be compared to a king who wished to settle accounts with his slaves. When he began the reckoning, one who owed him ten thousand talents was brought to him; and, as he could not pay, his lord ordered him to be sold, together with his wife and children and all his possessions, and payment to be made. So the slave fell on his knees before him, saying, "Have patience with me, and I will pay you everything." And out of pity for him, the lord of that slave released him and forgave him the debt. But that same slave, as he went out, came upon one of his fellow slaves who owed him a hundred denarii; and seizing him by the throat, he said, "Pay what you owe." Then his fellow slave fell down and pleaded with him, "Have patience with me, and I will pay you." But he refused; then he went and threw him into prison until he would pay the debt. When his fellow slaves saw what had happened, they were greatly distressed, and the went and reported to their lord all that had taken place. Then his lord summoned him and said to him, "You wicked slave! I forgave you all that debt because you pleaded with me. Should you not have had mercy on your fellow slave, as I had mercy on you?" And in anger his lord handed him over to be tortured until he would pay his entire debt. So my heavenly Father will also do to every one of you, if you do not forgive your brother or sister from your heart."
-- Matthew 18: 23-35
The biggest thing I get from this section is that it's not enough to simply accept the forgiveness of God. If you don't forgive others, you won't end up in a great place. Which comes very close to the idea that your actions can determine whether you truly receive salvation or not.
I also think the Western world has a habit of glossing over just how prevalent the concept of slavery was back then. Not only are most of the players in this parable referred to as slaves, the lord was legally entitled to sell the slave, as well as the slave's wife and children. And it's simply presented as a fact of life. We can say that obviously God wouldn't endorse slavery as it's morally wrong (or that it wasn't actually slavery as we knew but barely qualified to what we define slavery as today). Yet the concept of slavery is so entwined in this parable, even up to the aspect of people being sold.
I'm pretty sure the overall point of the parable is the idea that if one is forgiven by God for something huge, it's incredibly hypocritical to turn around and refuse to forgive another person when what the other person did was done on a much smaller scale. But there's also an idea here that a person can in fact do something to release themselves from the debt, whereas the penal atonement theory teaches that you can't do anything, and Jesus paid the debt for you (Granted, it could easily be desperation, since the first slave owed a huge sum that he could probably never pay. Nor did he actually have to, as the lord forgave the debt, period).
The torture aspect also made me do a double-take. Odd. I can glide over reading the word "hell," as I'm kind of immune to that word because it's a rather common one. But the lord here is compared to the Heavenly Father, and the lord is also someone who handed the bad slave over to be tortured because the lord was angry over the hypocrisy. I understand the anger. But the lord/Heavenly Father actively handing someone over to be tortured is interesting to mesh with the idea of "God doesn't send people to hell, people send people to hell."