Any good commandment should, presumably, be rational. If it were irrational that’s a problem – because then any irrational claim can be made into a commandment. You need to be able to think about it and have it, basically, make sense.
Of the typical Decalogue, from the Bible, most of the commandments are pretty crap. I’ll presume a basic familiarity – you can look them up if you’re unaware of them. Let’s examine, as per Christopher Hitchens, why most of them are problematic:
1 + 2. “No gods before me” and “No graven images”. Neither of these are ethical advice – they are injunctions, and we can skip them outright.
3. “God’s name in vain”. What does this mean? No one seems to have consensus on this, which is sketchy, for a set of commandments if there’s interpretation and wiggle room.
4. “Keep the Sabbath”. Saturday, presumably, not Sunday. If God doesn’t exist, though, this is obviously meaningless. We want commandments that apply universally.
5. “Honor thy father and mother”. Interesting idea – unless your father and mother are dishonorable. Or abusive? What then?
6. “Thou shall not kill.” The Bible directly contradicts this. Like, a lot. Which is a shame, ’cause it’s a good one.
7. “Thou shall not commit adultery.” Not a bad idea. Not too practical, sadly.
8. “Thou shall not steal.” Good advice.
9. “False witness”. Also a good one – bearing false witness against thy neighbor is reprehensible.
10. “Coveting”. Lots of problems: 1) Equating women with farm animals, 2) Punishes “thought crime”, 3) Goes directly against human nature.
There are those who, on the contrary to the final point above, argue that it is our human nature to murder, steal, and so forth. I don’t think this is the case. I doubt civilization would have risen to where it is without some basic understanding of what makes society work. As some have said – I doubt the Jews would have made it to Sinai unless they already had some understanding that murder is wrong.
We have some basic, obvious, moral understanding, therefore, regardless of the Bible. We know, without the Bible telling us, that slavery is wrong. So since ethics can be rationally arrived at, without the “good book”, let’s arrive at some rationally-based ethics.
Salvaging what’s still useful from this mess, I find there are three good commandments worth saving, and, since the order doesn’t seem to matter, I’ll make them the first thee commandments of my own list, updated slightly for 21st century language, and slightly improved:
1. Thou shall not kill, torture, or eat other human beings.
2. Thou shall not steal.
3. Thou shall not bear false witness against other people, and shall respect the privacy of all persons.
Now for the obviously immoral omissions:
4. Thou shall never own another human as property.
5. Thou shall not commit or threaten sexual violence, nor engage in sexual activity with thy family.
I mean, incest, rape, and slavery are all pretty obvious – and yet somehow didn’t make the top ten. The next one is also fairly obvious, but a bit difficult to phrase concisely. So I’ve adapted the language from the UN Universal Declaration of Human Rights:
6. Thou shall treat all persons as being born free and equal, in dignity and rights, without any distinctions.
On to some clearly praiseworthy notions, which, upon a little reflection, should strike folks as very good ideas for any society:
7. Thou shall not harm children, and thou shall protect all children from harm.
8. Thou shall allow all to practice freedom of thought, opinion, and expression – and thou shall persecute any who despise such freedoms.
9. Those who do not follow these commandments will be considered criminals. Criminals shall be treated without cruelty, and with the aim of rehabilitation to rejoin society productively. If serious, prolonged attempts at rehabilitation be impossible, thou shall separate them from society indefinitely.
10. Thou art an animal, and shall live accordingly – as a mindful steward for the perpetuation of the Earth and the protection of the environment.
Personally, I think the adoption of these ten would mark a vast improvement moving forward into this young century, and beyond. It's not a perfect list, perhaps, for for a top ten I think it works.