They’re explicitly fighting to establish a Muslim theocracy, under sharia law.
It’s not akin to something like the American revolution, where you had a number of religious people fighting to establish a secular country.
It’s more like the Maccabean revolt, where the Jewish leaders were the priests, and ended with the establishment of the Hasmonean dynasty where the high priest became king.
Would you really argue that the Maccabean revolt had nothing to do with religion?