Luther's obsessive focus on faith alone as the means of salvation, then, wasn't just about the problems with thinking you can logically prove the existence of God, it was also about power. No institution could get between people and God and claim to control the truth about God, because everyone could and should know God for themselves, directly. That's why the earliest translators of the Bible were treated so harshly: if everyone gets to read the Bible, then the priests don't get to control that knowledge about God.
In that sense, it's fitting that fundamentalist Christianity in the US overlaps so much with the sort of far-right politics that wants to do away with the government. No one else gets to tell us what the Bible says: we read it for ourselves. No one else gets power over me. But actually, what happens in most fundamentalist churches is just that power is better hidden. You can't not interpret the Bible, but you can appropriate its authority for yourself by pretending (or believing) that you interpretation is just 'what the Bible says'. It's harder to argue with someone who's just telling you what the Bible says than it is to argue with someone else's interpretation of the Bible. Truth is simply objective, obvious, accessible to everyone: it always comes to us through people, through institutions. The question of how we know the truth about God is never just a question about how we know the truth about God, it's always also a question about who in the Church gets to have power over other people.