In Romans 7:20 Paul makes the claim that, “Now if I do what I do not want to do, it is no longer I who do it, but it is sin living in me that does it.” So Paul believes that sin lives inside us and acts against our will. This would seem to undermine traditional arguments based upon free will. The spirit is willing, but the flesh is weak (Mt 26:41)
Of course, what Paul seems to be talking about, from a modern perspective, is biological or hormonal urges. Your body has certain physical reactions that are reflexive and do not even go through the higher brain. Your heart rate quickens. Males may get an erection. Certain things like this are not 100% under conscious control. Indeed, modern physiology tells us that the brain has many layers, and some of these lower layers, around the amygdala, for example, are concerned with the more base instincts of fear and gratification.
Yet Christianity still sets impossible standards, saying that we should avoid these things over which we have little or no control. Jesus, in Matthew 5:27-28 says, for example, “You have heard it said, 'Do not commit adultery.' But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.” This may even be the basis for Christian opposition to pornography, for example.
It is easy to demolish this silly claim, and once one does then Christians will resort to some sort of mind reading act about Jesus saying, “(I think) what Jesus meant was that you should try to control yourself,” etc, etc. The really slippery ones will then go back and try to quibble about wording after the fact, so it is also important to *pre-test* them and ask them, “Is it committing adultery or not, as Jesus says, to look at a woman lustfully? Answer yes or no right here:____” As I have said, later on they will come back to a single word to try to equivocate and pretend that you did not force them to change their view.
To quickly summarize the arguments against Jesus's belief that thought crimes are equivalent to real crimes, let us start with food. Gluttony, is one of the seven deadly sins, so imagine eating mountains of cake and ice cream. Oh, wait, Jesus says that it's wrong to even look lustfully at a pie. It's the same as being a real glutton, despite the fact that you haven't gained an ounce or deprived anyone else of a single morsel of food. Please hold off on the mind-reading apologetics, because I'm not done beating on this silly teaching of Jesus. If you imagine killing someone that may not be a good thing. It might lead to the real thing, but it might not. It might relieve your anger to imagine it for an instant, just as it might relieve your sexual tensions to look at a woman lustfully. Furthermore, and here's the clincher, if just imagining a forbidden act like adultery is the same as doing it, then why not go all the way and rape her, especially if nobody is around and you can get away with it? God says you have already committed adultery and presumably will already be punished for it. So why not actually follow your fantasies or vague intentions?
At this point, the Christian shouts, “A ha, I've found an excuse!” (in their own minds). They finally realize, via the thought experiment, that there is a difference between the physical act of adultery and the vague mental intentions. Thinking “Damn, she's hot” is a lot different than throwing her down and raping her. However, under no circumstances will they admit that it was your discussion which caused them to see the passage differently, because then they might have to admit that their faith can be changed or shaken. Instead, they will say, “Jesus says the act was only committed ...'in his heart',” versus “in her vagina”, so Jesus is off the hook for saying its totally the same. Not so fast.
To begin with, that effectively means that Jesus is saying nothing, because he is just restating the obvious that when you imagine doing something bad that you have committed an imaginary crime. So should you just burn in “imaginary hell” instead of the real thing? Is imagining being the King of England even close to actually being King of England, especially if you cannot really become the king of England? Then why is imagining sex with someone even comparable to the physical act?
Secondly, nobody said that Jesus didn't know the difference between a thought and an action. We all do. But Jesus is confusing himself and others when he suggests that there effectively is not much difference. Again, you can attempt to deny this, because, like many ancient holy men, Jesus's teachings were vague and incomplete. However, why compare a mental act to a physical act with no additional qualifications, unless you are suggesting an equivalence. When an adulterer commits real adultery, there are presumably thoughts that go with these actions. Jesus is saying that there is no difference between the bad thoughts of the real adulterer and the imaginary adulterer, despite the fact that one acts and one does not. Yet most of us know that there has to be some difference in thoughts, because, in one case, the person's thoughts emboldened him to act, and in the other case the thoughts did not. The thoughts that lead to actual, physical adultery surely had to be more serious in their intentions and more grounded in the real, physical world. Fantasy thoughts of sex with another women may be more generic and not even involve a specific woman, or, if they do, may never be with the serious intention of following through. Why should we be punished for thinking about things that we know we won't actually be able to do? We might imagine having sex with Beyonce, but we know it won't happen. It might be an impure thought, but it's not one that leads to any kind of action. Therefore it's still not as impure as the thoughts of the many men who have had sex with Beyonce.
So what is the substance of this teaching. You can imagine anything, but that doesn't automatically make you take on the character of the individuals who might do these things in reality. It's pretty clear that Jesus is trying to discourage us from thinking lustful thoughts, but his “argument” seems to be absurdly weak, since thinking about a given thing is nowhere even close to that actual thing. The only workable defense is to deny that Jesus was doing any more than making an empty statement about lust producing an imaginary crime. Since he never specifies the penalties for imaginary crimes there is nothing that can really be done with this teaching. Perhaps he wants us to imagine good thoughts, but, even there, imagining them and doing them are quite different things, and we should be hesitant to grant too much credit or blame for things that never leave our own minds.