There are no sects of islam that don't accept the prophet's actions as holy and unconditionally right. There are only differences about what those actions were,

There are no sects of islam that don't accept the prophet's actions as holy and unconditionally right. There are only differences about what those actions were, famously whether he appointed Ali as caliph or not (that's the difference between sunni and shi'a islam). All schools except one are part of all sects, all sects share all hadith, just not all hadith interpretations (they, and their many addendums and rewritten versions -very roughly- correspond to what is meant by a "school"). This is part of the islamic canon, which as I said is shared by all sects. Frankly, if this isn't in a sect, nobody would call them an islamic sect, but something else (example : the Baha'i, which originate from within islam, but nobody seriously considers muslims, merely because they disagree that the actions of the prophet were the "final" authority on morality. Their claim is that moral authority is to be found in any number of individuals, and that muhammad's teachings (especially the more insane ones) can and have been overridden. For this, there is a standing death penalty for any Baha'i that gets caught in >20 muslim countries. This mostly to illustrate that the vast majority of muslims accept the Bint Marwan story as moral authority, and that dozens of muslim countries consider it reasonable to execute people for not doing so). I would also like to point out that killing for insults to islam is quite popular amongst muslims, even in the west. And frankly, we can't realistically tolerate even 1% of them having this opinion (because it'll lead to events like the Hebdo ones). But even in general you're wrong "in practice". There are 2 islamic sects worth mentioning : sunni islam (~82%) and twelver shi'a (~13%). Yes the remainder has a million sects but, they're outlawed and persecuted in islamic nations, and their numbers are tiny. Furthermore, given that Christianity is both older and much richer in spread (meaning it's spread in more varied cultures), much larger number of adherents, and variety (many Christian sects in single locations), so I'd be extremely surprised if there were more offshoots of islam (unlike islam, Christianity seems to leave older cultures mostly intact. Comparing South America with Indonesia, for example. In Indonesia, the old culture is completely erased. This makes regional branches of Christianity have their own identity, and leads to offshoots, whereas the violent repression that islam historically was spread by did not exactly promote diversity)