I'm not sure where you're getting these impression. It's the left-wing types that think that the old nativity scene on the courthouse lawn is a political football, while at the same time promoting the latest education fad through programs in public schools.
Libertarians are generally strict on public dollar spending across the board.
To a point, but start a thread about prayer before a football game and Libertarians flock to that thread against such an abuse of tax dollars, eventhough no extra tax dollars were really spent. Believe me, there is a lot more vigor involved on the part of Libertarians when it is religious speech.