What’s the problem with theocratic law? Why shouldn’t we clap our hands and dance around the room when archbishops and imams suggest or insist that we should or must make our pesky secular system of law conform to God’s will or a Holy Book or ‘divine justice’? Why would we not want to do that and why is it illegitimate to try to force us to?

Because, whatever they may tell you, nobody knows what God’s will is, nobody knows that there is such a thing as a Holy Book, nobody knows what the divine will is. There is no reason to think there is a ‘God’ – even if there is a ‘God’ there still is no reason to think so, and no way to know what it thinks is justice, or if its idea of justice bears any resemblance to ours or rather looks much more like injustice, or wanton cruelty for the sake of it. We don’t know, we have no way to know, there is no reason to think we do know, there are only claims, which are indistinguishable from claims that could be made by any con artist. If there is no way to tell such claims apart, then there is no reason to believe any of them, and certainly no reason to demand that anyone else believe them, much less to mix them up with the law. Law has to be transparent and on the record, not hidden and mysterious and attributed to a supernatural realm that we can’t get at, or to allegedly divine or prophetic or holy people who died many centuries ago.

Lee Smolin made a helpful point in his Edge comment on Jerry Coyne’s ‘Seeing and Believing’:

The basic ethics of an open and free society are to be prepared to defend what you believe with reasoned argument from public evidence, be prepared to change your mind, and be tolerant of diverse views on questions the evidence does not suffice to decide. Religious faith that promises great gifts in a mythical hereafter as the reward for adherence to unverifiable claims contradicts these ethics.

Law belongs in the realm where we defend our claims with reasoned argument from public evidence and are prepared to change our minds, not the realm where we are bribed and threatened by means of unverifiable claims.