You can only say, if A is true, and if B is true, then what can we logically deduce from that. But you have to make the initial decision to regard that A is true and B is true.
For me one of the most convincing aspects of Christianity is just how unintuitive it is. Why would God let himself be killed? Why would a God wash the feet of the lowest in society? If you wanted to craft a religion to take over so much of the world that we count the years by it, how could someone possibly know that would be the way to do it? Either there is some truth to it or the people who apparently just made it up were super geniuses.
As to the particulars of the imagined God, actually we do have some evidence for the parameters. The Princess Alice experiments in particular illustrate one desirable property, God (in the experiment, "Princess Alice") should provides behavioural oversight. An imaginary being can deliver effective oversight which would otherwise require advanced technology, but to do so the being must also believe in these arbitrary moral rules.
And that matches what we observe. People do buy Sithrak T-shirts, but, more or less without exception they don't actually worship Sithrak, whereas loads of people have worshipped various deities with locally reasonable seeming moral codes and do to this day.
I'm guessing you're one of those people who thinks atheism means a belief in the absence of a god, rather than its actual meaning, which is an absence of a belief in a god.
Nah that's just what atheists convince themselves. There's nothing obviously nor truthful about this conclusion or the line of reasoning behind it.
All arguments for and against the existence of God are inherently unfalsifiable, but that doesn't mean atheism is inherently more logical than theism.
In fact, from my point of view, the existence of God is way more logically sound than the alternative, and atheists are the ones following delusions and worshipping their own egos