Eliminating religion wouldn't solve anything. People would hop on to something else. Nationalism, for example. Extremism happens for a reason.
What needs to be highlighted is science and education, or lack thereof. Christianity still exists in Europe but science and education are advanced and its extremism is pretty much irrelevant at the moment. Wasn't always the case. During Medieval times, Muslim nations were at their Golden Age, leading science while Christendom was in its dark ages, sinking in bigotry and extremism. Tables have turned. The difference is education, freedom and science. Not religion.
People already hop onto nationalism though, regardless of their views concerning religion. It's not like nationalism isn't a problem. The difference between them both though is that nationalism comes very much from a core idea, but with religion, it's anything goes since it's very much open to interpretation. Remember when a head executioner from ISIS was decapitated for smoking a cigarette?
You do raise a valid point concerning the Muslim golden age, the Arabian empire being a fantastic example, dedicating themselves not to plunder or worldy wealth, but rather culture, society and science, using faith as their driving force. Religions did a huge amount back in times old to help people concerning education and shelter for those less fortunate. But as our society, technology and philosophy advanced, religion never did. Now the same options that only the churches, mosques etc provided are now provided regardless in the form of schools, shelters, charities and so forth, therefore the advantages that those services originally had are now obsolete. What's more, with that advancement, people saw religion as false hope and by extension, glorified cults that only served to move the world apart as opposed to bring it together. Religion now just accentuates the negatives it brings, such as denying basic human rights, promoting prejudice and fueling atrocities like the one in Paris yesterday. It's really come to a head this century that religion is serving as nothing more than counter-productive to our development as a race. And whilst I appreciate what it has done for people in the past, we have reached a point where we need to move on.
Also, just a disclaimer. I treat anyone who has a religious view equally as well as anyone who is not religious, or who is atheist or agnostic. I don't hate people who are religious, I hate the idea.
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I never said there wasn't any extremism in Islamic Golden Age. You asked me if I thought that, and I answered with "They did have it but it was around as much as Christendom has now". There's extremism everywhere, but its relevancy is a different issue. If you think Islam was not a positive influence on science in the Medieval times, you're just not well informed. It absolutely was.