Apart from homosexuality, the Old Testament forbids many things we do today: Working on the Sabbath (Exodus 31:14-15) (penalty: death); eating pork (Leviticus 11:7-8) and seafood (Leviticus 11:9-12); pre-marital sex (at least for women) (Deuteronomy 22:20-21) (penalty: death); and wearing mixed materials, to name a few.

On the other hand, the Bible allows selling one's children as slaves, and lays out a complex set of rules governing slavery (Leviticus 25:44-52, Exodus 21:1-11 and 20-21).

The Bible also condones rape under certain conditions (Deuteronomy 22:28-29) and moreover forces the victim to marry the rapist.

In March Amina Filali committed suicide rather than marry her rapist under Morocco's barbaric law.

Apart from occasionally wishing we could sell our troublesome brats, in the civilised world we have moved on from the morality of 3000 BC. We no longer practise slavery, nor regard women as commodities whose virginity is more valuable than the person.

We do not stone to death people who gather sticks on the Sabbath (Numbers 15:32-36).

To our credit, modern morality is not based on the Bible, but rather on a consensus of fairness and tolerance developed gradually over centuries. This applies across most countries, irrespective of religion - or freedom from religion.

"Ah, but," the religious apologist may contend, "we now follow the New Testament and Christ's teaching that we treat others the way we want them to treat us" (Luke 6:31).

Fine. Then how about applying this principle to gay marriage too?