I pose this unlikely scenario to ask this question: is morality relevant to Bob moving forward? Christian apologists argue that morality is an objective truth that transcends human experience. If this is accurate then hypothetical Bob still has valid morals to follow. Granted, most Biblical laws don’t apply to Bob’s situation. He can’t very well kill, steal from, or covet his neighbor’s wife, for example; he has no neighbor. However, Bob can surely violate some religious rules. He could masturbate, he could make a false idol, he could have any number of impure thoughts, or he could attempt to make love to an irradiated buffalo corpse (which, incidentally, is a great way for him to speed up the inevitable extinction of humanity.)
According to secular definitions of morality, Bob can do no wrong in his lonely existence. Morality as the right way to interact with others, is meaningless without others. As the last living creature with the capacity to define morality, Bob can do whatever he damn well pleases. It takes at least two minds for a code of conduct to be agreed upon or for morality to emerge. At least that's how I see it.
P.S. It’s worth noting that I declared “It takes at least two minds for morality to emerge” to an apologist during a standard “moral argument for God” debate--and he agreed with me! I was shocked until he counted God as one of the minds. Does that mean that we’ll have to agree to disagree to agree?
P.P.S. I imagine God’s Mind gets capitalized as with every divine trait. Maybe Divine should be capitalize as well, it’s unclear. I’m sure they’d go ahead a subscript words mocking God if they could.