Why Political Islam is so popular
According to Wagemakers, the Arab world was searching for a new identity after 1967. This identity became Islam. While each country's 'Islamisation' process was different, they all came to existence against the same backdrop.
War against Israel
The Arab loss in the Six-Day War against Israel played a big role in this. The Arab sense of self took a hit after the war, and the search for a new identity led them to Islam. Furthermore, Saudi Arabia felt threatened by the revolutionary ideologies present in the region. As a counteroffense, the country steered itself into a conservative Islamic direction, which got spread to other Muslim countries.