I've never seen an argument work on an atheist.
You probably mean a critical thinker. You know what his rules for belief are. If you meet that standard, you will be believed. Here's what theists rarely consider - that they are wrong about gods existing or manifesting. If they are, they will never be able to make a compelling argument that they exist. And that's why
In my opinion, two legitimate reasons not to believe in God are as follows: 1. There is no proof that God exists 2. There is too much suffering in the world for God to exist
The legitimate reason to not believe in gods is that there is insufficient evidence to believe. The empiricist waits for a finding (evidence) that requires positing a god to explain before invoking that hypothesis. Presently, there is none - no evidence that isn't consistent with a godless, naturalistic universe.
I believe there are also legitimate reasons to believe in God as either position can be argued and justified with reason.
There is no intellectual justification for a god belief - no sound argument that ends, "therefore God" - but there are psychological benefits for some, especially older believers. I would encourage younger theists to choose humanism and critical thinking / empiricism. That's when I made the transition, which has beneficially informed my life since. But would it now? I don't see how. It's a lot like travel. Seeing the world when younger beneficially informs one's worldview for decades to come, but if one waits until old age, it's harder and just entertainment anyway at that point.
Does falsifiable mean true?
No. It means that if a statement is false, one can imagine a finding that demonstrates that fact. It's a rule to confine claims to those that describe what can be experienced rather than metaphysical claims. So, the claims of the theory of evolution could potentially be disproved if they are wrong. I say potentially, because one can also imagine that it is untrue, and that falsifying evidence exists but is never found - hence the word imagine. Imagine that a dog gave birth to a cat one day without technical intervention. Goodbye theory. Hence, the theory is falsifiable. But the claims of creationists are different. Even if correct, no evidence of that can be conceived of (imagined) - at least not by me or anybody else to my knowledge.
Belief in God is not contrary to the evidence since there is no evidence that suggests that God does not exist.
And there never will be even if that is the case, because the claim is unfalsifiable. What conceivable finding could rule the possibility of gods out? None to my knowledge.
But you need to be careful when capitalizing it and not using an article - "God" verses "a god." God usually means a specific god. Some of those CAN be ruled out, including the one most commonly called God in the West. The god of Genesis has been ruled out. There is no honest god that created the earth and life on it as described in the Christian Bible. Do you recall the argument? The theory of evolution, if correct, rules that out, but what if evolution were falsified tomorrow? What must be true about the origin of life on earth were that to happen if not naturalistic evolution? There was a deceptive intelligent designer, albeit not necessarily a supernatural one. Extraterrestrials would be more likely, but that's not the main point. Even were it a god, it's not that god. It's more of a Satan or Puck or Loki kind of god.
This is very much unlike Trump losing the election, since there was plenty of evidence that demonstrated that Trump lost the election.
An interesting comparison. It was never demonstrated that the election was fair. What was demonstrated is that there is no evidence that it was unfair. Are those the same thing? I'd say no. When a jury declares not guilty, they are not saying that innocence has been demonstrated, merely that guilt has not.
But we justifiably believe that the election was fair because we don't believe that if it weren't, that could be covered up following multiple audits and recounts of the allegedly most egregious elections. Why? Because absence of expected evidence is evidence of absence, which can elevate belief to beyond a reasonable doubt, but not to disproof.
And this is where gods find themselves as well. We can never demonstrate their nonexistence, just the absence of evidence of their existence, which is not the same, but is treated the same. Everywhere we look that might reveal evidence of a god if one existed ends up being a dead end. The believers in such gods tell us why their gods perfectly imitate their own nonexistence, but after awhile, they have dozens of just-so stores. The reason this god doesn't interfere with free will is that it doesn't want to. The reason its holy books seem like they were written by men is yadda. The reason why this god never manifests except in hearsay is yadda. The reason why children suffer and die of leukemia is yadda. The reason science contradicts scripture is yadda.
I've offered the metaphor of the loaded coin to you before. There exists a coin that many believe is a fair coin, but we are not allowed or able to weigh it or X-ray it to definitively demonstrate that it is a normal, evenly balanced coin. The only test we can do is watch it flip and tally the results. The coin keeps coming up tails. Believers in a fair coin explain after five tails that that is normal for a fair coin. Then it's twenty consecutive tails. Well, that can happen, too. Then a hundred. And then a thousand straight tails. Eventually, concluding that the coin is loaded is the parsimonious explanation for that, but it's never been demonstrated definitively the way we could if we had access to the coin.
This is what I have called the argument by restricted choice. A fair coin can come up heads or tails, but a loaded one only tails. A universe with a god in it might show evidence of that god or it might not (heads or tails), but a godless universe will always manifest as godless (tails).
Now consider your comment in the light of this. I say that we have the same kind of evidence that gods don't manifest in nature that we have that fraud didn't manifest in the election - strong evidence that can never rise to proof.
It is true that if the description of God runs contrary to factual evidence then we know that kind of God cannot exist, but that doesn't mean that there is no God that exists.