It all comes back to one thing. Islam is predicated on the notion that the world is subject to Islam whether it knows it or not, and muslims are called upon to make it clear to the world.
I, on the other hand, think that islam is full of crap if they think that I will ever pay their tax or speak their words.
If Centanni is wondering whether he is officially muslim, he needs to start rethinking his whole life, because he apparently doesn't know what he was before.
I don't think he meant he was unsure so much in the spiritual sense as in the legal sense, whether it was recognized by muslims as legally binding. In American law, we know that a contract made under duress is not valid, but apparently that is not so under Islamic law. They seem to take the view that you received a valuable consideration (keeping your head on your shoulders) for entering into a contract (conversion) with them, and so you are legally bound whether or not your heart was really in it. And the penalty for breaking this contract is death.