Well of course religions are not composed of saints. Neither are atheists (which include Stalinists, as well as more peaceful Objectivists and libertarians).
I'm a libertarian, Commie Basher. I'm also a Christian.
Political belief doesn't determine religious belief. Believe it or not, there are conservative Republicans who don't believe in God, and communists who do believe in God.
Our Founding Fathers were libertarian, and I don't think anyone would ever accuse them of being atheists.
I'm well aware of all of the above. Even so, a disproportionately large number of librtarians are also atheists. It's partly due to the historic roots of the recent (past 30 years) libertarian movement, which was led or influenced by secular/atheistic Jews (e.g., Murray Rothbard, and the Objectivist influence of Rand, the Brandons, Piekoff), and less so by secular/atheistic Catholics (Jerome Tuccille). Karl Hess (a Protestant?) was also not much into religion.
Of course there are "Bible-believing Christian" libertarians, but they are relatively latecomers to modern libertarianism.
Our Founding Fathers were libertarian, and I don't think anyone would ever accuse them of being atheists.
Oh, you'd find disagreement on both scores. Not everyone would call them libertarians, and many of them were deists, which some contend was a cover for atheists. I've also heard Ben Franklin, Thomas Jefferson, and Tom Paine accused of atheism, although I'm not sure how accurately.