In the public sphere, that is (or should be) true.
I do feel like there is a bit of nuance missing from this free speech vs freedom of religion debate, though. Just because one is
allowed (in the sense that there are no legal impediments) to exercise one's right to free speech and depict anyone you want in cartoon form, does not mean that you
should do that, or that doing it is "right" or desirable. Indeed, drawing (or publishing/displaying) cartons of the prophet Muhammad may very well mark you out as a complete arsehole in many/most circumstances. Of course you have a right to be an arsehole, but everyone else has a right to direct commensurate levels of criticism your way as a result. This, in my view, should also be true of Holocaust denial (ie you should be perfectly free to deny the Holocaust, and everyone else should in turn be free to publicly admonish you and boycott your business).
All of the above is only relevant with regards to the public sphere, though. In schools or places of work, there are additional rules that we must follow and standards by which we must abide. What might be allowable in public is not necessarily appropriate for a school setting.
@Carolina Red has made a case for using satirical materials such as the ones alleged to have been displayed in Batley, in an educational setting, and I think it is possible to conceive of a context in which these cartoons could perhaps be used in an appropriate manner. In the specific case of Batley, however, we still have vanishingly little information to go on regarding context and therefore it's surely sensible to reserve judgement.