Preservation of Christian identity in the process of integration

This morning father Gojko Perovic, dean of the orthodox seminary of Montenegro addressed the summer school about the preservation of Christian identity of communities in the process of (European) integration.
He started by observing that Christians are citizens of another kingdom, of a city that is yet to come. He referred to the French revolutionary philosopher Rousseau, who, for this same reason, argued that Christians can not be dependable citizens for a secular state. He then went on to speak about the Jews that preserved their community's identity when in exile in Egypt and Babylonia, while at the same time being actively involved in politics. The Jews did not have their own political party to defend their interest, but still some managed to preserve their identity to a large extent. We would expect them to have been fully assimilated.
Later on many authoritative Jewish authors realized that the dominance of Hellenic culture posed a greater threat to the Jewish identity. For example even priests were attending the games of gladiators. When the Hellenic dominance became to obvious and Romans invaded Israel, the Macabees fought them with guerilla tactics.
So the Jews preserved their identity even though they did not have their own state, but they were actively involved in politics.
This could be a model for us Christians: to preserve the identity of our community, while being actively involved in politics, but not identitfying with any political system.
Father Perovic then spoke about the relation between church and state in Montenegro. The inheritance of communism is that people are afraid to integrate their beliefs into politics. The relation between church and state is not described, but the religious communities want to take the lead in changing this and the European Christian Political Movement (ECPM) has been instrumental in this.