For people who dont think that the inherent evil in Islam is the cause of all the problems in the world (especially if you agree that Christianity, Judaism and other religions have a lot in common with Islam what would be considered unsavoury today), then this is my view on the rapid spread and disturbingly widespread support Islamists are finding in the world.
I think religion based political movements exist or have existed before dying out, everywhere in the world and have found widespread support amongst people who follow that particular religion at different times in history. Religious parties exist for every religion, who claim to be following the word of god, quite extreme to start with, but when faced with public unease, slowly re-aligning themselves to become more acceptable to mainstream. What has happened and is unique in terms of Islamism, is a consistent failure for it to make any headway politically.
One example is India where the national government - started as an extreme right wing religion based party, but slowly become more mainstream and now enjoys widespread support. They realized it would be impossible to defend their views once the attention was on them. If they tried, they would put people off in the next elections, hence they were forced to make themselves more palatable. Ofcourse there will always remain a slant, but they cannot remain out of touch with reality else they will not have a chance of getting in power.
Islamic political movements have not gone through this process, predominantly because geopolitical calibrations have always led to collapse of Islamist governements in the Arab world. If free and fair elections were held in middle east today, I think most will agree that Islamist parties will win. Whenever they have happened, it has been followed by a coup often backed by west, and crushing popular will often accompanied by imprisoning Islamist leaders and brutal crackdown on their supporters. Algeria 1992 or Egypt recently is just a couple of examples. Instead they have been forced to live with dictators they hate, or end up in a power vaccuum to be run by ruthless militias. Also, there are serious restrictions on following Islam in many of the so called muslim countries, where the dictators feel threatened by the Islamists. Many so called muslim countries have bans on wearing headscarf in various places while people with a beards or overtly religious symbols are seen with suspicion. The are serious restrictions on religious freedoms, not to mention minorities, but even on muslims themselves. Muslims in west enjoy much more religious freedom to even follow Islam than they can have in Middle East.
This fuels even more anger against the governments. Maghreb region has become a hotbed of Islamic terrorist activity precisely for this reason, with major terrorist activity being reported in Algeria, Libya, Morroco, Chad, Mali, Mauritania and Nigeria. But this is only a start. What is currently being ignored by many countries is central asia where the regimes in countries like Uzbekistan, Kazakastan and closer to home in Azerbaijan having brutalizing the population for decades and there is serious conflict brewing, like in the Ferghana valley. Again these countries are run by horrendously brutal dictators like Karimov, but they receive unlimited arms and support from the west, as long as the gas flows. How long can this last?
Due to these frustrations, people are supporting what are more and more extreme movements. I am afraid this will keep growing unless, genuine democracies are established in the region. They may throw up unpalatable results at the start, like Muslim Brotherhood in Egypt, but as long the democratic process is followed, they will be forced to become more mainstream, e.g. Ennahda in Tunisia and AKP in Turkey. They will always have a religious slant, but so do republicans in the US or a Likud in Israel. There needs to be an outlet for people's desire to have government which represents them ideologically.
A case in point is Iran, no matter how much it is attacked for various reasons in the western media, remains a functioning democracy, albeit a religious version of it. It helps balance the strongly religious people, at the same time accomodating the needs of more liberal section of the country. As people evolve, so will the political parties like the transition from Ahmedinejad to Rouhani. This all takes time and wont be done overnight. Atleast it will not lead to terrorism as long as people have legitimate means to express themselves politically.