Secular nations are en route to self-destruction via a catastrophically falling birthrate: fewer than 1.5 births per woman, when the replacement rate is at least 2.1 births per woman. To get the necessary manpower to pay the pensions to shrinking and aging populations, Europe is going to be overrun by Moslems.
In the US the situation is somewhat different: there are rapidly reproducing local groups, such as the Mormons, the Amish, the Hutterites, the Brethren. All are intensely religious, which means that the present predominatly secular public will lose control of the government, and yield it to such highly religious groups.
Perhaps here is the answer as to the conundrum as to why no tribe, no society, no culture, no civilization has survived the test of history. They all self-destructed due to the failure to reproduce.
