Can you dismiss other religions and peoples of the ramifications of #3 or are they just liars?
No they could not just be dismissed without investigation. And even though there are different beliefs about God it is the common belief among them all that there is a God that I think is the most worthy of investigation.
Although of course you take a lot for granted when you say there is a belief in "a god". Roughly 60% of the world believe in "a god" - of the rest, the split uis roughly equal between "no gods" and "many gods" - and if you track back through history, the split between "god" and "gods" narrows, reverses, and you get to a stage where all religions held a pantheon of different gods - including Christianity itself.
You need to also take into account the blurring that comes when you look closer in. Is Christianity the belief in "just" a single god? Never mind the trinity, what about belief in angels, for example. How does that compare with Chinese and Japanese religions, and their demons and spirits?
If that is considered evidence for your god, then all type of things now have evidence for them being real, such as UFOs, Bigfoot, ghosts, Loch Ness monster ... shall I go on?
Yes, and all of these things have merited investigation and some are more easily dismissed than others.
And lets add ghosts, to take but one belief. Spiritualists believe in a god, but also that ghosts exists. Chinese folk tales feature ghosts and spirits quite strongly - where (if anywhere) do we draw the line as to what does, and does not, merit investigation? And more to the point, where do you start? If I begin with "ghosts", how long do I search before deciding that the evidence simply isn't enough? And does "no evidence found for ghosts" equal "no eveidence found for afterlife", for example?
But perhaps more to the point, on anything more than the grossest and basest facts, I find witness statements to be singularly uncompelling. Unless we are talking about carefully controlled and documented observations, the more I learn about how the brain works and how easily it can be fooled, the less I accept eyewitness testimony, especially where "woo" comes into the equation.
Take a look at this picture. Focus on the little dot, and watch as your brain turns the moving bar from gray to blue.
Thnk about that for a while. The visual input does not change, the colour does not change, but your brain changes what it reports to you that you are seeing.
And that's just the tip of the iceberg, frankly.
And if you saw the Derren Brown "Fear and Faith" show, you'll have also seen how in the space of about 20 minutes, he set up enough psychological cues that a lifelong atheist had a powerful spiritual experience that pushed them a long way towards a god belief.....because they stood up. If you haven't seen the programme, watch it. It makes it clear how intensely powerful feelings can be experienced without the slightest bit of supernatural intervention.
So to the broad point - that testimony is evidence for supernatural experience - I am very, very skeptical. As a possible basis for investigation, sure. But ONLY as a basis for further investgation. Let us indeed establish what these experiences might suggest, and then let us critically examine and test them, the way we would cross-examine in court, the way we would test and test again in the lab, the way we would - when eyewitness testimony conflicts - look at the coroborating physical evidence.
And if, after we have critically examined the religious testimonies in the way we investigate a ghost, for example - without backing off for fear of offence, and without special treatment - then maybe we can determine how much weight this evidence should be given.