I had responded to the rest of your post, but it all boils down to the same thing. As Lewis' trilemma makes for a very interesting discussion, I'd like to focus there
So if Jesus' claims to divinity were untrue (i.e., he's not Lord), but he was not mentally ill (i.e., he's not a Lunatic), then the trilemma leaves us with only one possibility: he's a liar.
Correct.
But, what if he didn't know he was wrong about his claims to divinity, instead being quite genuine in his belief that he was God, perhaps coming to this conclusion by specious logic on his part? He isn't a liar by any usual definition, but as I just showed, Lewis' trilemma strongarms him into that pidgeon-hole, so we can only conclude that 'liar' now encompasses the unintentional utterance of untruths.
In clinical settings, people who claim to genuinely believe they are God, or Napoleon, or Alexander the Great, or any other person, are diagnosed as suffering from some sort of mental illness. Physicians do not diagnose it as a conclusion arrived at via rational thought processes in a normally functioning brain/mind via "specious logic". This simply is not a viable alternative. It is not strongarming or pidgeon holing anything.
However, ironically, your "specious logic" suggestion reinforces my point that people can come up with all kinds of nonsense to avoid coming to terms with reality. Why not just rather say that a person who really believes they are God and are not, is mentally ill?
The point is that the trilemma ignores a very real possibility and in doing so results in one of two things: it either becomes a false trichotomy, or it remains technically a true trichotomy by abusing the definition of 'liar' to encompass unintentional untruths.
If a person genuinely believes they are God, and are not, then they are deceived about who they really are. However this deception is generated is moot. They are deceived and living a lie. The question is:
Are the accounts we have of Jesus, the accounts of a man who is deceived, and or mentally ill?
My point is that the trichotomy is either false (it precludes very possible alternatives), or it stretches the definitions to their breaking point (making 'liar' encompass the unintentional utterance of an untruth). There's no two ways about it.
He is either God, a liar, or mentally ill, or a combination of the latter two.
The possibility exists that Jesus was simply a sane Rabbi who mistakenly concluded that he was the Messiah (look at
Harold Camping or the
Millerites for how completely rational people can use specious logic to come to very wrong conclusions). He was sane (so he wasn't a lunatic), he was genuine in his beliefs (so he wasn't a liar), but he was ultimately incorrect (so he wasn't lord). What, then, was he?
If He was not the Messiah, He was deceived. We was wrong about who He was. Since we have accounts of Him performing signs and wonders that would only have been possible if He were God, why not just rather admit He was God?
1. Jesus says He is God
2. He does things only God could do
3. He says things only God could rightfully say
Why not just say He is God?