Cultures must be better than others to survive.  That's no guarantee they will survive . . . only that they have a reason to try to survive.  

Religions are the same way.  Religions, born of perceptions of the supernatural and refined by interaction with nature, are at the heart of morals.  Western civilization and its component cultures are based on moral precepts based on Judeo-Christian religious values, but Western governments these days try to function independently of any particular religion.  I say try, because although these governments preside over robust cultures, they and their cultures begin faltering when they maintain rules based on religious principles while denying that the rules by which they operate have any historical grounding in religion whatsoever.

The guiding moral principles on which the members of society agree to operate and maintain order began with ancient religious principles, but are kept in place today because they are still good ideas.  The question arises whether these good ideas came to man from God or whether man discovered these rules on his own the hard way and then made God up afterward.  At this point, one wonders why man would bother to make God up if the rules for living were already obvious.  Since not all humans learned at the same time what works and what doesn't, perhaps God was conceived by the discoverers of the rules as a means to persuade others to obey the rules; God would be an all-powerful, supernatural enforcer who would be looking over one's shoulder and punishing transgressors, if not in this life then forever in the afterlife.

In fact, this seems to be the case in pre-Jewish or non-Jewish cultures that actually had rational moral codes.  The theory goes, though, that God intervened through the Jews after the human race kept stumbling, lost in the wilderness of its own logical constructs.

The United States, undisputedly the brightest light of Western civilization over the last two centuries, agonizes the most (and the most publicly) about acknowledging its religious roots.  But some people fear that acknowledging the relationship between man-made law and its religious roots will mean that they will be compelled to admit to a state-sponsored religion.  That's unreasonable but understandable given the secular revisionism of public schools, which has caused a decline in the ability of its students and graduates to think clearly.

In many European countries, religion has been suppressed in the interest of perfecting governments where religion need never be referenced, where anything supernatural has no place, where there is no invisible hand on one's shoulder to guide him, and where only an individual's conscience guides his behavior.  A sense of some common good or government compulsion is the only thing that keeps the individual European's behavior in line.  

In the Islamic world with the notable exception of Turkey, the idea that one can separate church and state is illogical and unacceptable.  This is a powerful one-two punch in the gut for our troops who fight for their own country, the greater good of civilization, and the right to worship their own way.  Muslims fight for their country, the entire Muslim brotherhood, and directly for a God who tells them that all people must worship Him or die, or, rather, be killed.  The doorway to Paradise opens for believers if and only if they murder infidels.  [This makes no sense to those reared in the Western tradition, but as Pope Benedict recalled in his Regensburg speech, the Islamic conception of Allah is that He is so transcendent that He is not bound to act in ways that make sense to humans.]  The synergistic relationship among mosque and state and the unification of interests of all members of the umma makes Muslims motivated fighters. The people they are fighting for at home are in complete solidarity with the jihadists.  Muslims permit themselves no opportunity to become morally confused.  

It's sad that Western soldiers are constantly reminded that they're putting their lives on the line for people who don't appreciate it.  This weakens the odds when G.I. Joe meets Jihad Joe.