Cults are incompatible when their doctrines contradict and entail taboos that conflict irreconcilably, in such a way that they cannot be practically and honestly and harmoniously honored by and in a man, or therefore in any society of men. E.g., one can’t live and render each his due unto Caesar and YHWH if Caesar insists that what belongs properly to YHWH should be given instead to him. No man can serve two masters, nor can any people.
When incompatible cults continuously interact, war between them is inevitable. The choice for Christians before the Edict of Milan was between apostasy and persecution. Rome was at war with Christianity.
Likewise today, it is more and more difficult to live as a Christian in the West. More and more, our choice is between apostasy and persecution: either we agree to live by the taboos of liberalism, implicitly rejecting those of Christianity, or we shall be persecuted. Islam and Christianity are likewise incompatible, as are Islam and liberalism. All of these cults but one will eventually be deleted.
Now it may be that taboos are taken lightly by one cult or another, so that people can get along, avoiding hot war with each other. It may be, in other words, that people make unprincipled exceptions. But what cannot be carried successfully into practice cannot be correct. If to live you must make unprincipled exceptions to the taboos of your cult, that is a sign of its weakness and poor fit to reality. Any such exception to the taboos of a cult is an implicit repudiation of it in act. When a people shrug off the taboos of a cult, they sap its moral relevance to their lives as lived, thus vitiating the cult itself, root and branch, thereby reducing its magnificence and influence – i.e., its ability to mount a convincing case for itself. Absent a Great Awakening of some sort that persuades men of the truth of its core dogmas and the importance of sticking with them even at the cost of conflict with neighbours, it must then fall into desuetude, as has happened to the Christianity of liberal Christians.
That vigorous incompatible cults are inevitably at war does not mean that violence is the only way the contest between them may be settled, and a victor known. Moral collapse of a cult is much likelier after a great military defeat, but such a defeat is not a prerequisite. The indiscipline and timidity – moral, and implicitly intellectual and practical – of a sufficient number of individual men can sap a cult of fortitude almost overnight, ushering in cynicism or despair, or both.
The morale of a cult may also collapse before a memetic onslaught that it cannot answer, either because it has no good arguments, or no will to make them, or no thumotic urge to resist such arguments as it cannot answer philosophically. Liberalism is radically incoherent, so it has no philosophical arguments that can work except by obfuscation. Cast a harsh and unforgiving light on liberal misdirection and incoherence, and you’ll get jerks of the knee, fueled by outrage at the violation of a sacred taboo. Liberalism is logically bankrupt. But then so is it gutless, and timorous. How not, when its adherents can make no good sense of it? Who can be courageous in defense of a mess of oxymorons and contradictions in terms? Or, how could any sane man think such a mess worthy of anything other than deletion from history, notwithstanding that it is his own?
Finally, cults can collapse because they obviously and spectacularly fail to work as well as their competitors, as happened with the Fall of the Warsaw Pact vis-à-vis the vigor of the capitalist West, and with the collapse of Classical Paganism before the demographic wave of Christian reproductive and commercial success. The logical bankruptcy of liberalism means that it can’t work in any world with conservation laws; so is it literally bankrupt – busted in every sense of that word.
Note that beauty is an aspect of working well. Chartres and Salisbury, Bach and Palestrina are effectual proposals for the proper organization of human life, arguments from beauty as sublimity of act congruent with and expressing the order of the cosmos to the truth of the cult that produced them via an apprehension of that order, and agreement with it. Cults that cannot produce such beauties can compete with Christianity on that score only by denigrating or destroying them.
Cult wars do not necessarily play out on battlefields. But one way or another, cults that preach incompatible taboos must war on some field or other until one emerges victorious, and predominant: if not the field of battle, then of wills or arguments.
Onward, then, Christian soldier.