An early shelf item: the existence of Jehovah's Witnesses

I've mentioned before my first shelf item, when I was eight and my primary teacher told me an angel had taken the gold plates into heaven, and therefore nobody could see them. A second shelf item came a few years later, when I was 12, and one of the leaders was talking mission stuff with another recently returned missionaries and they started mocking the "J-Dubbs" they would see on their mission. I asked what this meant, and they explained about the JWs' efforts, and how they sometimes muddied the waters for the missionaries where both were working the same town.

It struck me as incredibly weird these people going door to door and setting up kiosks in order to preach an obviously false gospel. Who would waste their time like that? And I had a startling realization. They didn't know they were wrong! They thought the Mormon missionaries were the ones who were lost and deluded.

Such an obvious observation, and yet it left me a little shaken. I couldn't answer how that could happen. If they were really sincere, surely they'd recognize the truth when they saw it, and even if they didn't, it would surely be far too pale of an imitation of the gospel to inspire anyone to do the kind of missionary work they seemed to be doing.