That's the general myth about it.
The law is not based on the acceptance of all religions as law, but rather that it views all religious beliefs from a neutral perspective and thus religious tenets and laws hold no value in a court of secular law. Each citizen is governed by exactly the same laws, regardless of their religious beliefs. This, in essence, makes every person equally liable to the law. Even should an individual rely totally on religious law, such an individual cannot be immunized from secular law on the basis that they personally hold themselves to a religious law, since such a practice would require every religious person to be held accountable to different degrees, by the law. This practice would be unenforceable, and thus the law of the land is based to take into account premises and principles that apply equally to every person, regardless of their personal beliefs.
To say that religion, Tintin, should inform law, is to say that there should be different laws for every person, since every person holds different beliefs.
There was a system something like this in Roman-occupied Jarusalem. There were Roman laws and Jewish laws.
