It's a popular line of thought, but so far as I can tell, not well founded. If you think Patton was right, you think that the statements:
1. There is no God.
2. People are of greater moral value than rocks.
are incompatible: if one is true, the other cannot be. But, on the face of it, I see no reason to think that. To make an argument, you'd need to introduce other, related, statements and back them up. (If you spend a lot of time debating this sort of stuff, you'll noticed I've taken a leaf from William Lane Craig's book. My response is pretty similar to his response to the logical Argument from Evil, where he points out that his opponents have just made statements without showing how the statements are logically related).
I mentioned this in the comments on Patton's post, and have been discussing it with The 27th Comrade. Comrade makes the weaker claim that "If God doesn't exist, it is not necessarily true that people are not rocks". He then goes on to claim that a person's value can only depend on a transcendent, immutable opinion; and that without God, there can be no objective moral values.
But I see no reason why, if there are moral facts independent of human opinions, they would be defined by the opinions of a (non-human) person. I also don't see how this makes values objective, since that word usually means "independent of anyone's opinion".
At this point, I mentioned the Euthyphro dilemma (which I apparently introduced to William: I'm glad someone's learning something from my ramblings). If God sets what is moral by his opinions, they seem arbitrary: God could have made anything moral by fiat. If God's moral opinions reflect some other independent facts (as my opinion that "the sky is blue" does, say), while God may well know the facts better than we do, the facts would still be facts if he did not exist.
If you've had some evangelism training, you'll know there's a popular response to the dilemma, which is to say that goodness is part of God's essential nature: not external to him, but not something he chooses. Craig adds that we understand what words like "good" mean without reference to God; it is informative, rather than tautologous, to learn that "God is essentially good". But it seems then that any being which had the morally good properties God is claimed to have would be good, whether or not that being existed. As John D says, "All that Craig is doing is ascribing certain moral properties to God, but it is these moral properties that provide the foundation for morality, not God. He is talking about necessary moral truths, not necessary theistic truths. In other words, morality is still not 'up to God', it merely inheres in him."
Comrade seems to have got diverted by my examples of horrifying things God could have made good by fiat. I was unclear here, and unfortunately I chose as examples some of the horrifying things the Christian God actually does in the Bible, which Comrade then felt compelled to defend (I often run into this problem with theists: with hindsight, I should have avoided the sensitive subject of racism when talking to robhu about complementarianism, but I had trouble thinking of an example of discrimination which evangelicals don't already think is a good thing). But that wasn't my point, which was rather that, if morality is based solely on God's opinion, there's no reason to suppose that God's opinion is anything like what we mean by "good" (notice that Craig is cannier here).
Comrade asserts that (edited: if there is no God) we have no basis to judge anything that has evolved as wrong, referring to Orgel's Second Rule: "evolution is cleverer than you are". But again, I see no more reason to identify "what has evolved" with "good" than I do to identify "God's opinion" with "good". Evolution may be clever, but clever isn't the same as good.
The psychology of moral arguments
What I take from this is that some people want different things from moral values than I do. Some people just intuitively feel that if there isn't a God, they can't get those things. What they seem to want is:
- Moral values must be "objective": this means they cannot be pure opinion, unless it's the opinion of someone they can always trust and who has much higher status than them.
- Moral values must be unchanging.
- Moral values must be "grounded": this word is often used. It's not clear what it means for morality to be grounded, but it gives us a strong visual image of grounded objects (at least, I assume you're also seeing a tree with an extensive root system underground), so suppose it does well as an intuition pump. God is supposed to be pretty solid, in non-physical sort of way: I hear he's a bit like a rock.