The Jews reckon there are 613 different laws in the first five books of the Bible, almost all of them in Exodus to Deuteronomy. I haven’t counted, but if they’re right, that’s nearly five in each chapter. If you’ve ever read Leviticus, Numbers or Deuteronomy, you might even think that’s an underestimate!

So how should we read the books of the Law? Law number 238 says we shouldn’t wear cloth of wool and linen mixed together (Deut. 22:11). Instinctively, almost all Christians would say that doesn’...