Theists: What is the most compelling argument you have heard for Atheism?

[SteveII]

The evidence is the fine-tuning. The argument discusses what we can infer from the evidence.

I disagree.  Fine tuning is an interpretation of the data.  It can't be evidence for itself.

No, fine tuning is not an interpretation. It is a fact, that the initial constants had to be in a mind-boggling narrow band of values for the universe to hold together, elements to form, galaxies to form, etc. See here for a another basic list: https://en.wikipedia.org/wiki/Fine-tuned...e#Examples

If you think this is just a fringe opinion, here is the bio of the guy who created the list. https://en.wikipedia.org/wiki/Martin_Rees

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The evidence is the fine-tuning. The argument discusses what we can infer from the evidence.

What evidence is there of fine tuning? All we have to go in fine tuning's existence is a presupposition made by certain people that the universe exists as it is is because humanity has to exist, an unjustifiable assertion.

This has been all gone over earlier in the thread. You are wrong about how we arrive at the conclusion: 

1. The fine-tuning of the universe is due to either physical necessity, chance, or design.
2. The fine-tuning of the universe is not due to physical necessity or chance.
3. Therefore, the fine-tuning of the universe is due to design.