In the postwar era, collective action in Eastern Europe was organized by atheist Communism. Adversarial collective action in Western Europe was organized by ethnic nationalism, gradually displaced by secular transnationalism. The shape of collective opposition to the Evil Empire by Western Europe was defined in terms of transnational unity, which required a secular framing due in part to the competing religious creeds of its constituent societies.
Adversarial collective action (and also social pacification) in the United States is defined by what is loosely termed 'patriotism' - a political construct with an integral religious component. The fact that the two appear to go hand in hand is not an accident.
Hmmm. Western Europe had Protestants and Catholics, and the US had Protestants and Catholics. I failed to notice any great need to paper over religious differences in Europe with transnational structures. That was done to for economic and defense reasons.