The interesting question here, in my opinion, is how groups with a belief in some kind of transcendent, or higher, truth can acheive peaceful cooexistence with others in a society which doesn't fully conform to their concept of truth or the good. This is more or less
the question of the latter part of the career of the political philosopher John Rawls. At points Rawls directly discusses the issue of gaining religious support - see, for example, sections 3.1- 3.2 in The Idea of Public Reason Revisited," Chicago Law Review (1997), 64 (3): 765-807. Of course, in broader terms, Rawls is also famous for providing a modern political philosophy, owing much to the social contract tradition, aiming to show how basic institutions could be jsutified - liberties, law, taxation.
In terms of participation in a community featuring divergent views a minimum condition is that one accept some kind of principle of tolerance (one might disagree with or even actively hate a set of beliefs, but it is important to tolerate them - with the caveat, which so upsets the anarchists, 'unless they act in violation of the norms established by accepted, coercive law'). I was interested to learn that in 1965 the Catholic church passed a declaration on religious freedom, and thus toleration, called
Dignitatus Humanae. Such a declaration offers the grounds required for Catholicism to coexist in the context of modern, pluralist democracies. Apparently some (fringe? I don't really know the discipline)
scholars have suggested that the seeds of tolerance and constitutional openness can be found in Shari'a law provided that greater emphasis is placed on Muhammad's earlier Mecca teachings.
