I do think believing that you are a deity is a sufficiently far fetched falsehood to justify calling you a lunatic. For the sake of argument I suppose I'm willing to accept "profoundly confused individual" as a fourth alternative. But I don't think it helps the rhetorical point against painting arguments for "lord lunatic or liar" as an unjustified demand for absolute beliefs.
And no, you're not a lunatic for believing someone else's bullshit.
