That schism is completely unnecessary. Religion is religion. Libertarianism is a political philosphy. They're aren't incompatible because they are not competing for the same thing. Fascism, communism, liberarlism, conservatism, etc. are incompatible with libertarianism because they are all political philosophies.
In a wider context they are.
Things are either true or false, beliefs are either rational or not.
Of course Libertarian beliefs don't have any inextricable connection to religion or non religion,
however, the fundamental reasoning behind both concepts are(unless you believe in a moral system based on preference and not objective standard).
Whether it is moral to arrest people for victimless crimes can be answered by logic and reason. Whether it is reasonable to believe in the existence of gods can also be addressed by those same mental tools.
The same reason I don't believe Communism is correct is the same reason I don't believe any religion is correct. All beliefs (should) come from rational critical thinking, and thereby all beliefs are on some level linked in their veracity.
The shuttering off of "religious" or "spiritual" beliefs from other beliefs is one of the most irrational, and intellectually cowardly behaviors people engage in.
To believe that certain beliefs should just be a matter of personal preference, of what "works for you", is an extreme disparagement of the value of those ideas.
Either your god exists or it doesn't. If it does, you should care about proving it, just like how libertarians should care about proving to other people. The only time I ever see people trying to diminish the objectivity of reality in this way are people who are afraid of having their beliefs proved wrong.
If you truly believe that there is some afterlife and omnipotent super being, and that having that belief is important, and may even decide where you spend eternity, you should (in my opinion), take as many chances as you can get to persuade people against the irrationality of not believing in X god.
Likewise, if you believe religions are idiotic superstition, merely a human invention based on the fear of death and the confusion over the nature of existence, then shouldn't you seek to dissuade people, especially ones you care about, for wasting literally years of their life over false rituals and irrational beliefs?
to me I don't really care what you believe, as long as you're willing to rationally debate it, and you care about whether its true or not. Everyone starts off in life with a whole bunch of faulty beliefs, its how ardently you seek to pursue truth and discard falsehood that determines how much bullshit you manage to shake off, and how accurate your view of reality is
fuck non-proselytizing theists
and non-theists