Confessionalism is an ideology that varies per country it's practiced in, being either economically centrist and cultrually rightwing in the Netherlands, or just a layer of bureaucracy in states like Israel or Lebanon. Typically confessionalism means "representation of religion in politics"
Differences per country
Iraq
After the American invasion of Iraq a system was esthablished, although not official but traditional, that required power to be shared between the main three ethnic groups of Iraq, Sunni Arabs, Shi'ite Arabs and Kurds, with the President being a kurd, Speaker of Parliament being a Sunni Arab and the Prime-Minister a shiíte arab.
Israel
Among other limitations, political parties cannot deny that "Israel is a state of the Jewish people"
Lebanon
Half the seats in parliament are reserved for ethnic groups that aren't islamic lebanese, most prominently christians.
Netherlands
In the Netherlands confessional parties generally adopt a economically centrist and culturally rightwing program to base their politics on, that program being influenced by the bible. The term was coined to mark the effective fuse of catholic and protestant ideologies into one ideology. Old confessional parties have later adopted christian democracy instead.
Relationships
TBD