I have heard people say many times that “sin is sin.” “All sin is equal.” The problem with this is that it is certainly never stated in the Bible and I believe that it actually contradicts the Bible. If we look at the Law of Moses, it definitely made a distinction between willful and non-willful/accidental sin. In Leviticus 4:22-23, Lev 5:14 (and many others) talks about “unintentional sin.” The Law of Moses had no sacrifice to cover intentional sin/willful rebellion against God. In Hebrews 10:26-31 the Hebrew writer makes a distinction about willful sin. He tells us that continual, willful sin will disqualify us from eternal life. Willful sin is rebellion and is, in the Old Testament, punishable upon two or three eye-witnesses. How much worse for us, the Hebrew writer tells us, if we continually and willfully sin.
So, there are levels and types and degrees of sin and of retribution. Exactly how that works is not described in much detail in the Bible, but that there is a distinction is plain.
Now, exactly what Jesus means in Matthew 10:15 is not stated. We have to make reasonable inference. What we can say is that Jesus believes that what those who refused to listen to Jesus–to God in the flesh–were more subject to judgment than the residents of Sodom and Gomorrah. This is a shocking statement, is it not? The intensity of the evil of their sin is great, not just that they did not listen, but that they did not listen to God-in-the-flesh. To reject the teaching of Jesus is to willfully rebel against God himself. This is the unforgivable sin–to hear Jesus and to purposefully reject what he says.
I do not think this justifies us developing a detailed list, from the worst to the least bad sin. Only God can do that, and he did not decide to do it, so we should leave this alone. What we should understand is that direct rebellion against Jesus is the worst sort of sin. Whether that rebellion is murder, adultery or simply not going to church, it is in relation to the stubbornness of our hearts, not which sin is committed. This is the unforgivable sin–to willfully and continually sin against God after being forgiven of our sins.