Lack of good apologetics
As with direct evidence, theists have had thousands of years to figure out what their gods are like, what they want, how they operate, and so forth. And yet, there are no good apologetics or arguments for any god’s existence. Most of them rely on false dichotomies, or faulty reasoning, or faulty assumptions, or are otherwise flawed.
In fact, one of the most popular apologetic arguments, Pascal’s wager explicitly begins with the premise that the existence or nonexistence of God cannot be known. This is not an argument that you pull out if there’s direct evidence of the truth of your claim. And yet, it comes up all the time.
In fact, many bad arguments keep coming back over and over. There appears to be no mechanism (selective pressure, if you will) for getting rid of bad arguments.
One running theme that I’ve noticed is that a lot of apologetic claims are not arguments for a god, but rather excuses for the lack of evidence, or excuses to reinforce someone’s failing belief. “You need to have faith” is just “trust me” in fancy clothes. “God doesn’t want to show himself for fear of undermining our free will” isn’t an argument, it’s an excuse for the absence of evidence. In fact, so is the whole “faith is a good thing” constellation of memes (which people don’t believe anyway, but we’ll address that later).
The world of apologetics is littered with arguments that, in any other context, would be relegated to the bottom of the barrel. Perhaps the most famous of these is Tertullian’s “Credo quia absurdum” — “I believe it because it is absurd”. Whether you take that as “I believe weird things” or as “The apostles wouldn’t have tried so hard to convince us of something that wasn’t true”, it still doesn’t belong on anyone’s top 10 list.
“I can feel Jesus in my heart” is just “dude, I’m telling you, I saw it!”. It’s something you resort to when you don’t have anything better.
“God works through people” just means that people do remarkable things. It’s not an argument for the existence of a god, it’s another excuse for the absence of evidence.
Now, people will say that esteemed theologians don’t use bad arguments like “well, just look at the trees and the birds and stuff”, and that’s mostly true. However, their arguments tend to be flawed in other ways. C.S. Lewis’s famous trilemma, Liar, Lunatic or Lord ignores possibilities like “Legend” (which also fits the alliteration). This is an elementary logical flaw that Lewis himself, if not one of his early reviewers, should have spotted.
Alvin Plantinga has come up with a version of the ontological argument for the existence of God, which relies on certain properties of modal logic. I don’t claim to understand it. On the other hand, presumably a lot of philosophers do, and I’m not hearing a lot of conversion stories about philosophers converting to Plantinga’s brand of theism.
In fact, that’s a running theme: there are simple arguments that people cite when asked why they believe in gods, all of which are wrong. And then there are the sophisticated complex arguments, but no one is convinced by those. It’s almost as if the complex arguments are just excuses to believe; if they sound complicated enough, you can pretend that they’re sound, and rest assured that somewhere out there, someone has a good justification for your faith.