Joshua wants to know why “the sin that leads to death” isn’t simply the rejection of Jesus’ humanity that characterized the Gnostics of John’s time (2 John v. 7)?
This is a good question and one I had not thought considered when I wrote an earlier post on this subject, but I certainly see how it could arise. After all, if a person denying Jesus’ humanity was in John’s words, “the antichrist” (2 John v. 7), then I see how someone might think it is the sin leading to death. Maybe I should too, but I’m not convinced that’s what John has in mind when he speaks of the sin leading to death.
Some sins are worse than others. We know that because Christ said so (John 19:11). The Old Testament clearly regarded premediated killing as worse than the accidental taking of someone’s life (Numbers 35::20-25). In the same way, the NT identifies certain sins that, due to their nature, bring (almost) immediate separation from God. Paul will speak of some who were circumcised because they had more trust in Jewish rituals than in Jesus as having “fallen away from grace” (Galatians 5:4). Similarly, the Hebrew writer speaks of those who have turned their back on Christ’s sacrifice to return to the Jewish system and says, “no sacrifice for sins is left” (10:26ff). I think the sin of denying Christ’s humanity belongs in this category. To embrace it is to separate yourself from God and His saving work through Christ.
That said, any of these sins can be repented of. In fact, Jesus said something about the possibility of those speaking against Him being forgiven (Matthew 10:31-32). Suppose someone in John’s time had believed Jesus didn’t come in the flesh and then changed their mind about it and embraced the incarnation. Well, that would be wonderful, but if they didn’t regard their previous view as sinful since they still didn’t believe they were capable of sinning, it wouldn’t make any difference, would it? That’s why I think the sin leading to death is a reference to those holding the attitude spoken against in 1 John 1:8-10.
Something else to consider is that there would have been no reason to think that people couldn’t have embraced certain aspects of Gnosticism without embracing others. (Think of how many people embrace a few of the teachings of Jesus while rejecting others). We don’t know for certain that was going on, but we don’t know it wasn’t either. We do know that John chose to address the denial of sin aspect of Gnosticism separately and early in his first letter.