Not every Libertarian is an atheist, it's just that everyone of them that I have met is an athiest.
There are a whole bunch of religious people in the leadership of the anarcho-capitalist movement: Catholic, Protestant and Jewish. Ludwig von Mises was Jewish. If you read anything at lewrockwell.com, you will find that most there are pro-Trump, anti-Hillary and anti-Bush to varying degrees. The Beltway libertarians (Koch-tarians) are not truly libertarian at all, in the same way that Bushes are not conservative. About half of the libertarians online are Christian, that I am aware of. The opposition to tariffs among libertarians is primarily concerned with taxation and not trade. I would like to see tariffs replace the income tax personally. But I would also cut the federal budget to the bone...