That's the question.
And the real answer is - you can be almost completely wrong, and at a fundamental level; and most people are: nearly everybody is.
An arrogant statement? Probably - the question is: is it true?
Obviously nobody is likely to take anybody else's word for it, when it comes to the accusation that they are fundamentally wrong about most things; but if that is the actual situation, then somehow or another, sooner or later, this is something each will need to work-out for himself.
Change one, change all... once a single piece is removed from the machine of falseness (once we see through one of the Big Lies), then the machine breaks, incoherence is evident.
(That's where we are now, in the mainstream West.)
The usual response is to replace the missing piece as quickly as possible: to get 'things' working...
But if, instead, we refuse to go back to what we now know to be a lie - we will then remove another piece (another fundamental assumption) from our world picture, in the attempt to restore coherence. And find that instead this makes matters even worse!
Our world view is now crumbling, and every step we take to try and restore cohesion actually makes matters worse!
That's the way it is, when we have been living a complete lie, such as modern mainstream godless Leftism; and then attempt to live by a not-quite-so-bad falseness - such as the mainstream offers as possible alternatives - e.g. the so-called 'right wing' parties, the 'radical' ideologies', the traditionalist conservatives...
What we are left-with, at the end of all removal of wrongness; is something very simple, very basic, very easy to understand - some thing that is absolutely impossible even to speak of without seeming dumb, crazy or (by pragmatic standards) wicked...
That is exactly where we are. The true answer is pretty obvious and can be reached by anybody, even a child: especially a child.
But what when the coherent and true answer turns out to be Not an answer we can 'work with' in any kind of social, cooperative, public or organised way...
Well... then, again, each much decide for himself.
Note added: The above argument is intended to apply primarily to Christianity, also to any ideology; but also to politics. For example, if the current Brexit turns-out to be a genuine Brexit, this constitutes a qualitative reversal of many decades of a trend towards globalist system of totalitarian leftism. It is exactly the kind of thing I am talking about. Of itself, it is a small - almost insignificant - subtraction from the whole; but of itself, Brexit makes no sense in the context of how things are going; and therefore logically leads to undoing the change; or, if not, then more change, in the same direction.