I didn't say this is what you said. I simply commented on the way I see most Christians consider sin. They seem to be convinced they don't sin because they know the Bible and, per their understanding of the Bible, they are convinced they do not sin but it is not possible to avoid sinning by mere intellectual understanding. The only way to avoid sinning it not to believe or to understand, it is to see.
The way I view it, the mere fact of overlooking there is a problem with Revelation 1:5 is a sin. It's as if I said to someone: "bummer, there is a stain on your shirt" and they would look at their shirt, see the stain without acknowledging it then reply: "no, there isn't" just because they paid a lot of money for that shirt and the salesperson told them it's made out of a special cloth that cannot be stained so the wearer won't see the stain because they just don't want it to be there. The problem is, everyone can see the stain and, by not acknowledging it, the person wearing the shirt cannot take it off and wash it. That illustrates the problem with believing rather than seeing.
In the same way, most Christians are convinced that questioning the Bible is a sin when it is really the other way around. By not acknowledging the 'stains', most Christians make a joke of Jesus' teachings and they are responsible for many people to turn their back on Jesus. You see the problem? Those who see the stain view the Bible as a joke, which they wouldn't if Christians simply admitted there is a 'stain'. Failing to do so, hence driving millions away from Jesus' teachings, is a serious sin, way more serious than it could ever be to question parts of the Bible.