Suppose I were a highly advanced extraterrestrial being and I had decided to pay your planet a little visit. Suppose further, that I had very specific expectations for my arrival. I have provided expections so that you can follow them. Some of the residents of insane asylums are providing the instructions. In order that you know that I am serious, I have also provided pictures of my craft -- in crayon. They sort of look like the drawings of 4-year-olds.
Now, in this scenario, I decree that anyone not conforming to my expectations will be tortured. Since I have provided such convincing evidence (though none has seen me directly) all such people are "without excuse."
Do you think that this would be morally justified? I think it is highly analogous to the biblical claims. If the biblical god actually exists, shows up, and punishes non-believers for their non-belief (let's face facts; the "it's for your sin" is simply false) he is an immoral monster.