Within the broad boundaries of Christendom, Catholics have the Pope, Anglicans have the Archbishop of Canterbury, some denominations have appointed and/or elected leaders, while still others, such as Congregationalists, insist on no hierarchy. Buddhists have several leaders, the most well-known being the Dalai Lama. Judaism is complicated by the melange of culture, race, and religion, so while there is no specific leader, chief rabbis speak to matters of doctrine.
Islam has its scholars (for Sunnis, the Ulama) and Imams, but the famously fractious faith has no head. It needs one.
In the absence of a global leader, Muslims are told to simply obey the Quran and hadiths. That might be a workable solution if both sources weren't subject to everlasting debate within and without Islam, and complicated for non-Muslims by the practice of taquiya and kithman. The month of Ramadan is upon us, and while the vast majority of Muslims regard it as a time for reflection and self-control demonstrated through fasting and other prescribed rituals, extremists view it as the ideal time for jihad. Such schisms aren't merely intellectual when spilled blood is a clockwork result.