The rule is religion neutral. The same principle that is used to argue against religious exemptions from “gay rights” legislation applies to this. Weaken this rule and you create an argument for religious opt-out of almost any law. Besides, the rule does not interfere with her ability to practice her religion. It just specifies that she can’t cover her head on the floor of the House. If it is obligatory on Muslims to do that, she can just resign her seat. Islam does not demand that its adherents be Congress members.