When I was 13 or 14, there was a television show on one of the networks. There was a guy on, I don't remember who now, but he claimed that we all have powers of the mind. If we think hard enough, if we focus our energy, we can unlock these powers, he did various demonstrations. He talked to audience members and told them about their personal lives. He claimed to have read their minds. He also performed other stunts. About midway through the show he said, "I'm going to demonstrate to everyone out there today that they, too, have powers they can unlock." Well, this, obviously grabbed my attention. He told everyone at home to find something that isn't working and put it near them. Then he told the audience at home to shout, "Work! Work! Work!" over and over again. Keep focusing on the object. Keep shouting. Unlock the power of your mind. No one was in my house at the time. I had a broken watch that quit working months ago. So, I did what he told me to do. I focused every thought on the watch working. I shouted (wonder what the neighbors thought). After a few minutes he stopped and said, "Now there are those at home that know they have power. I want those people to call the number at the bottom of the screen and tell us what happened." My watch didn't do anything. But, I kept watching the show. People started to call in. "I had this blender, it hasn't worked in months. But, I focused my thoughts on it and shouted, 'Work!' and when I plugged it in, it worked!" one caller said. Another call came in and they had lawn mower, and it started working after years of sitting in the garage. Caller after caller told how they unlocked the power of their mind. Why didn't it work for me? Do I discount their claims? There were a lot of people that called in. A few years ago, when I started listening to skeptic podcasts, one of the podcasts talked about a similar incident on a foreign tv channel. Just like my experience people began to call the show with similar claims. How could the skeptic podcast deny what had happened? What was their explanation? Well, the various stunts from the show were tricks of cold reading and other similar things. Things that are well known to magicians. A magician started the podcast to explain how magicians fool people into thinking that they can read minds. The part about the audience calling in, they explained, is a game of odds. The audience for this performer is in the millions. If only a small percentage of people in the audience had some unexplained phenomenon occur, they would see that as proof for what the performer was claiming. A very large number of people would experience what I experienced and nothing would happen. But, if you take that small percentage and showcase them in front of the others, that small percentage can convince millions. With such a large percentage of people there's bound to be a few people that experienced something. They would have screeners to make sure only the most convincing stories would make it on air. I'm sure a lot of people leave events like that completely convinced in the power of the mind. But, when your anomaly hunting, and there's no pass or fail requirement, eventually you will find something to confirm for you your belief, no matter what that belief is.
I've had several Christians tell me about how they've experienced a miracle. Sometimes, it's just getting a job at the right time. Or receiving a check in the mail they weren't expecting. But, a lot of times it's about how they prayed for something and it happened. And, that for them, that is all the convincing they need to believe God is real and he did something for them. But, it's no different than having a million people shouting for something, anything, to happen and believing they have special powers. There is no criteria for what counts as a miracle. A miracle is whatever they want it to be. If it means that you found a leak in a pipe before it burst, that's God. If it's a narrowly missed car accident, that's God. There is no way to test whether or not it's actually God. It's God if you believe it is. There is no false criteria. If you pray and nothing happens, that evidence will be ignored. If you pray and something happens, then your bias to believe is confirmed and you will use that as an example to all your non-believing friends.
The problem is subjective testimony in and of itself isn't very convincing evidence. To be convincing, you would have to have an objective demonstration or an explanation about the mechanism that makes the testimony plausible. If you were to tell me that you can read my mind, I'd doubt that. Because that isn't my experience of how the universe works. But, you told me that you have a functional MRI that can read brain patterns and will allow you to piece together a pattern on a computer that can be compared to other patterns that will give you an idea about what I might be thinking, that I could accept. You've given a plausible mechanism that would, in fact, allow you to read a mind.
"But, God isn't a mechanism, He's a being and he can't be expected to give you reproducible results in a lab. He may act when someone prays, he may not. You can't ignore all the testimony that God acts in others lives even in this day and age." When any evidence is exempt from confirmation through some sort of objective filter, I question the testimony. Confirmation bias is a lot like throwing darts at a wall and drawing bulls eyes wherever the darts happen to land. There is no way to verify the claim. There is no way to reproduce the claim. There is no way to demonstrate a cause and effect relationship. And, in the end this sort of testimony, simply isn't convincing in any way.