Emphasis added:

Moreover, all of this is contingent upon you being found out. In a scenario like this, is that really that likely?

Yes. It is.

It sounds like you're implying that most lies are easily found

In a scenario like this, i.e. pretending to be undergoing a deep crisis of faith in order to undermine someone else's. My observation is that in practice, concern trolling is rapidly found out, and the bigger the audience, the shorter the time to being nailed.

thinking all people are only as good at lying (at max) as you are at sniffing them out.

On the whole, people are as good at lying as, on the whole, people are at finding them out, because it's an arms race. Some will do better, some worse; anyone to whom the idea, "why not just lie!" has only just occurred is unlikely to be in the former class.