Civilizations believe things. If they didn't believe things, they couldn't be civilizations.
Nothing ever gets built, whether pyramid or skyscraper, if everybody is just wandering around in aimless little circles muttering that whatever they think is simply their opinion, which of course could be wrong. That kind of behavior does go on, of course, but only when a civilization is down to its fin de siecling of the drain. That's how they fall apart, not how they get built.
Now if these civilizations are very conceited, or if they don't get out much, they frequently may not know that they believe certain fundamental truths -- they just chalk all that stuff up to what "everybody knows." When the occasional person shows up who doesn't "know" that stuff, he is dismissed as a sociopath, mentally ill, a religious nut, or a terrorist. But such epistemological naïveté is really indefensible -- and unfortunate in our case, because Western values currently are under attack, and whenever you are under attack, indefensible is not the adjective you want to have riding your noun.
Now this explains a great deal about why Christians who are actively engaged with issues in the public square usually get the reaction they do. (I leave out of this analysis the reaction that some Christians get when they decorate leftist dogma with random Bible tinsel. They already have their reward, which appears to be some kind of empathy grok with the spirit of the age.) The secular elite wants to act as though biblical Christians are breaking the rules by intruding purely religious concerns into an arena that ought to be entirely a-religious. They want to believe the problem is that the Christians are appealing to a particular God, when the real problem is that they are appealing to a rival God. The issue is never "no God or God," but rather "the establishment God or the rival." When Christians start to act in a way that threatens to reveal that there actually is an established and embedded god of the system, the reactions can be spectacular -- what Moliere, with his unerring instinct for the mot juste, might have called "freaking out."
Another way of saying this is that religious systems are inescapable. I am not in the habit of quoting Tillich favorably, but I don't do it much, and so I beg to be forgiven just this once. No individual, no group of individuals, and no culture can fail to have an ultimate concern. When you have found their ultimate concern, you have found the object of their faith -- their foundational religious commitment. Every society has one, and after we have dealt with the reality and inescapability of that, we should endeavor to find the right one.
Some religions have candles and altars, and some of them don't. The way secularists try to plead that they are not religious at all because they don't have the accoutrements that other "denominations" have is mystifying. It is like Catholics claiming that Shakers aren't religious because they don't have prayer books, or Shakers arguing that Catholics can't be religious because they do.
Secularism is a faith, plain and simple -- every culture has a cultus, a system of worship at the center. We are no different, and so our high claims of religious neutrality are therefore a sham, a pretense, a fraud, chicanery, duplicity, a civic hustle, a fast one, a bit of flim-flammery, and any other relevant terms of disapprobation.
I wrote earlier of "Western values." What are those? The West was not built by the secularists, but it has been hollowed out by them. Jesus once compared two men who built two houses, one on sand and the other on the rock. He then compared what happened to the two houses when the storm hit them. Left out of His parable was the option of initially building a house on rock, but then going off to college and taking one philosophy course too many, and coming home again in order to have the house moved to a sandier location, but one with a better view of man's endless potential and innate goodness.
Whenever you deny that ever-present realities are not actually present, the result is simply confusion. Very few Christians think that they can be Christian and Muslim at the same time, or Christian and Buddhist. But quite a few have been maneuvered into thinking that it is possible to be Christian and secularist. Of course, it is physically possible, but this is because syncretism has always been possible. People have been trying to split the difference for a long time.
But as Joshua told the people a long time ago, when he missed a great opportunity for inter-faith dialog, the time had come for choosing (Josh 24:15).