Why it is madness?

The color of skin is no more relevant to anything than color of hair. You can know the percentage of, say, red-haired people in your country, but what for? The only thing where that could be needed is to fight e.g. some Dark Ages prejudices against red-haired people, and this is expected to be a marginal issue, not some all-encompassing national program.

The same goes for religion. In Europe, religion is inherently private endeavour.

It's important to know that government dealings in Sweden, and that includes databases, falls under the principle of publicity unless specifically exempt. That means government officials must make the information available to anyone who asks without delay or imposing a fee. (It's often a surprise to newcomers that information about earnings and taxes is public to anyone, but you get used to it being an equal right for all.) That's part of the reason policial and religious afflictions are forbidden to store.

> That last part is madness.

Europe has had a lot of bad experiences when it comes to how we've treated our minorities, and the census has often been used as a tool for finding "undesirables". And I'm not only talking about countries like Germany here; Sweden had a policy of forced sterilisation for reasons of "racial hygiene", that it didn't discontinue until 1975.

http://www.temple.edu/tempress/titles/1625_reg.html

I think you misunderstood. Sweden has a census, they just don't have a voter roll you can look up to see what race your neighbour is or what party they belong to.

Yes, you can collect racial statistics, but the thing that is expressly prohibited is to make a registry where you connect a person with these attributes.

The idea is that it should be impossible to, for example, get a list of all the communists in an area, or all the homosexuals, or all the moslems, or everyone of African descent.

It's a defense of minorities against a future fascist government. Which I think is kind of neat.

Why?