benkei : I don't care about German law. What I was saying is, there shouldn't be any recognised religion. Religion is a private matter that neither should be invaded by state matters (freedom of spirituality) nor invade state matters itself (state-religion separation). What I'm saying is, it is wrong and un-secular for a state to recognise individual religions and give any kind of authority in matters that regard the state and the state only (case in point, the law). Individuals can consider themselves part of a religious group and be open about it if they want just like their sexual orientation (as long as it is not proselytism). They can follow religious "laws" if they want to and be "judged" by their religious authorities if they want to as long as everything is actually legal by state laws. It shouldn't be the responsibility of the state to ensure people affiliated with a given religion don't eat X, just because that religion has many followers. Religious neutrality is not giving concessions based on the size of arbitrary religious groups, it is ignoring religion altogether. People having "problems" just because their religion is forbidding/forcing them to do illegal things have only themselves to blame.
This is precisely what I'm talking about when I say that's not how freedom of religion works. You, as an individual, are allowed to have any spiritual belief you like. You can invent imaginary do's and don'ts to make your life harder for yourself if you like. However You cannot force others to do anything based on those rules you have chosen for yourself. This is a private and strictly individual matter. If those personal rules makes you do things that are outright illegal (e.g. the lamb sacrifice), you are commiting a crime, and you have only yourself to blame. You alone have decided to be religious, precisely because you have the freedom to choose. As an atheist I can also sacrifice a lamb, and just because I'm an atheist doesn't mean I shouldn't be treated the exact same way. We are both humans and equal in rights, that is all that should matter.
Just to show how ridiculous the whole idea of "reasonable exceptions" goes, what if tomorrow the whole atheist population pushed for say, banning paper ? We could all pretend our beliefs prevent us from using paper.
edit : just spotted a missing "not"
To clarify: This is not about the state passing laws, enforcing religious rules or allowing criminality because it's ok in the criminals religion. This is simply about the question how existing law (which is perfectly fair and neutral imo) is applicated.
It is allowed to excuse yourself from compulsory service if that entails doing things which are against your convictions. For example the state doesn't force vegans to eat meat. It also doesn't force Jews to eat non-kosher meat (freedom of spirituality). So both groups can excuse themselves from cooking lessons where meat is made. In that case it was about a Muslim wanting to be excused from swimming because it was against her religion. They were asking religious authorities in the context of whether that was actually the case and if they should accept the excuse. This is all that is about.
If you'd want to avoid that in the first place and reject the reasons outright as Muslim/religious, that'd be you trying to force a religion/value set on the state, unless you are not accepting any excuses. Which would probably entail tying a vegetarian to a chair and force feed him meat. Sounds terribly funny, but I think I'll still stick with the more liberal way (hell, since this is about swimming, I'd actually consider "I just don't feel like it" a valid excuse to be honest - how far it goes plays a big role also, obviously, good luck trying to fund a religion which is against taxes).
In any case this is far removed from any actual integration problems, since real problem kids and their parents do not care the slightest about failing school.