I thank you god

The first time I read over this poem quickly, I thought it was sarcastic.  The line, "...human merely being doubt unimaginable You?" was what most made me think that.  It just seemed really extreme to say that it's impossible to doubt because I can see how many would and could doubt.  Also, the fact that he doesn't capitalize "i" seems extreme, like he's saying people aren't worthy of it, but God is.  I guess the extent to which he praised god gave it a mocking tone to me.
But the more I read it, the more I believed he believed.  Also, looking at the time period, it wasn't really during a time full of doubt.  He just seemed to genuinely and truly love god.  And that's where I got disappointing in the poem.  It just turned into a gospel to me.  It was sweet and made me want to have an admiration for something like he did, but then I was over it.  It seemed like he was having a moment where everything was great and god was great, which is heartwarming, but slightly boring.
And now, Mrs White, I feel like you're turning me into a pessimist.