The telltale signs are the expectations of differentiated treatment according to belief stance
Do you mean expectations that non-Muslims treat Muslims differently from those of other faiths?
of privilege of theistic claims over more concrete social and scientific concerns
By this criterion, I am an 'Islamist' or 'extremist Muslim'.
and of bending of laws and customs once Muslim majorities are attained in some specific region.
This doesn't seem unreasonable to me (although I would say the same might hold true when any group attains a majority in a particular region - one could say that is democracy). Does this make me an 'Islamist' or 'extremist Muslim'?
Islam is remarkably heterogeneous when confronted with its own hopes, but remarkably homogeneous when contrasted with most other ideologies and religions.
Can you give some examples of the homogeneity you see in Islam?