I agree up to a point. I don't believe in a categorical imperative. Ethics is not algebra, after all. The problem is that if we say all rationalisations fall back upon axioms, we are being trite. The fact that at some point you hit the axiomatic buffers doesn't mean that there is no point in justifying anything. I think that route logically leads to the conclusion that good and evil are meaningless concepts, and while it's an intellectually consistent viewpoint, it's not one I find particularly attractive. I am probably oversimplyfying your (plural) position, and if so I apologise for not having grasped it properly, but it feels like the argument you are making is analogous to saying "because we can't know everything, there's no point in knowing anything". Fundamentally, if religion can't explain to me why I'm not able to work on the Sabbath, for example, then it's unreasonable to expect me not to. I am not a small child, and I require reasons not to eat all the sweets. ("The last ten times you did it you were ill" would be sufficient, but I need some assurance more than a vague feeling that God isn't just saying that because he wants all the sweets for himself.)