It isn’t so much the hijab itself that is offensive, in my view, but the moral obligation to wear it. A woman wants to wear a hijab? That should be fine. A woman wants to wear a string bikini? That should be equally fine. (Side note: men with stupid haircuts are equally allowed to sport them.)
The problem is when women are forced to dress a certain way for the men in their lives. A woman should not take the blame for a man’s impure thoughts, but that is exactly the thought process behind women wearing the hijab for religious reasons.
Similarly, if a woman wishes to be subject to a man to the point of following his every order, we have no right to tell her to stop. When she feels she is morally obligated to do so, there is a problem.
As for respecting other’s beliefs, I refuse to respect any beliefs that cannot be supported by evidence or good reasoning, and I especially refuse to respect any beliefs which are contrary to the overwhelming scientific evidence, such as creationism. As long as the holder of such beliefs is not likely to become hurt or hurt others because of them, I have little problem with letting them live and not seeking them out to attack their beliefs. However, I will attack such beliefs as harshly and as often as I wish on this blog; I just won’t attack the people.
The Complete History of the Universe: A Personal Journey 