The extremism of the Islamic State in Iraq and al-Sham (ISIS), in belief and practice, is a despicable phenomenon that must be contained and condemned. But it should also be acknowledged that ISIS is only a symptom of a larger problem - a problem that goes to the heart of the extremisms of the modern world, the failure of the international system, the sense of despair and nihilism, political and economic injustice and the uneasy relationship between tradition and modernity.Like all extremist movements, whether religious or secular, ISIS can seek to justify its extremism by referring to Islamic sources, such as the Quran or the life of the Prophet Muhammad. As numerous Muslim scholars and thinkers point out, a misguided methodology and misplaced ideology can be used to distort any religious text and historical precedent. Al-Qaida, Boko Haram and now ISIS all use or rather misuse religious sources and references to create an extremist ideology.To counter this, a large group of Muslim jurists, scholars, intellectuals and academics wrote an open letter to al-Baghdadi, the presumed leader of ISIS, showing in great detail and with authority how ISIS's violent extremism against Muslims of other sects and people of other religions is rejected by Islamic tradition. The core message of this letter is supported by millions of mainstream and moderate Muslims around the world.No one has the right to use religion to justify what is essentially and primarily a worldly goal: power. ISIS and its spokespeople may quote verses from the Quran or shout "Allah akbar" (God is great). But this does not make their acts religious or sacred. The Quran itself warns against those who try to manipulate the commands of God for their own benefits. ISIS is a typical example of a power-seeking violent organization that uses religious justification but eventually fails at logical consistency and religious authority. The problem is that not all extremism is necessarily religion-based. Extremism does not need religion to emerge. Nor does it need to remain faithful to the true spirit of religion to carry out its violent acts.The extremisms of the world in which we live provide a plethora of material for any movement to go to extremes. There is a long list of extremism that comes in different form: the two world wars of the last century, occupations, economic and cultural colonialism, billions of dollars spent on armament, weapons of mass destruction, the widening gap between the rich and the poor, the extreme individualism of modern societies, drugs, the brutalities of modern capitalism, human trafficking, climate change, environmental crisis, the poisoning of our food, water and air, technology-dependence reaching new heights, and violent movies, violent video games...These and many other forms of extremism have crept into our daily lives, political discourses, educational systems, economic policies and many other areas of our life-world. They force ordinary people to take extreme positions, whether in perception and attitude or in practice, on all key issues. By turning a blind eye to these, we only delude ourselves. We cannot reduce extremism to violent killings only. Those killings, as carried out by ISIS recently for instance, must be rejected and stopped. But we should not lose sight of the larger picture here: We live in an age of extremities whereby doing something in a middle and moderate way is not cool or does not register or is rejected as insufficient to get what you want. In many subtle and not so subtle ways, the current system of political and economic relations force people to the margins and to the extremes. Those who carry on with their lives in their own modest and moderate ways are not heard, respected or even protected. Only when you start making a lot of noise and become violent does the system begin to pay attention to you.In all extremist movements, there is a fine line between taking a firm and radical position for justice and tripping over to extremism. There are places where one has to be radical and uncompromising: When you have the duty to protect women and children, human rights, the rights of minorities, fight against the occupation of your country and fight against terrorism. But where this morally justified radicalism ends and where violent extremism begins is where things get delicate and sensitive. The extremities of the modern world make it extremely easy to take that step from being morally firm and uncompromising to turning into a violent extremism.This is where we need a reassessment of our modern priorities and critically question the overall direction of the present state of humanity. Rejecting extremism in all of its forms, whether ISIS terrorism, sectarian killings, school shootings or Hollywood violence, will be a first step in the right direction.