What is Islamism? A Muslim*Replies
The key difference between Islam and Islamism is that Islam is not, and has never been described as, a political ideology.
Furthermore, one could even argue that there is in fact scriptural justification for the separation of Church and State in Islam, so that there is no real scriptural justification for establishing an Islamic state as Islamists maintain. I refer to the saying of the Prophet Muhammad (pbuh) “You know your worldly affairs better than I do, and I know your religious matters better than you do” (Muslim ‐ 139‐141). Many have interpreted this to mean that although the Prophet was a religious and political leader, he was not infallible when it came to politics and that Islam makes no prescriptions about the way human beings should organize the political realm while on earth.
It is thus in marked contrast to both the history of Muslim societies and world majority Muslim opinion that even today the Islamists regard Islam axiomatically as a revolutionary political ideology surpassing all other political ideologies, such as Communism and Capitalism, since it is a divine ideology rather than one based on fallible man‐made concepts and ideas. An implication of this is the Islamist assertion that Islam must have provided a detailed and divinely pre‐ordained stance on matters such as political structure or the economy and these can be realized, by definition, only by destroying institutions based on Capitalism and Communism which have no basis in the Qur’an. If these structures and systems are deemed absent, the Islamists will work to bring them about.
https://religion-compass.com/2009/11/19/what-is-islamism/
