One time, Ludwig Wittgenstein was walking around by the pond with Bertrand Russel. Bertie said, "People treat the ancients as if they're terribly silly for thinking that the sun went around the earth. I think this is unfair; that is how it looks, after all." Ludwig said, in reply, "Oh really? How would it look if it were the other way 'round?"
(This never happened, by the way, this is a philosophical folk story. I suppose Wittgenstein would like being remembered for something that never happened, though.)
Sometimes, after music time in church, I hear people say, 'I really felt God moving in that time of worship. The music was so good.' It's rarer that I hear people say, 'The musicians made a lot of terrible mistakes, but, in God's sovereignty, I felt his presence, regardless.'
At one point in my life, I kept a daily journal to track problems with insomnia. I recorded things like when I ate and exercised and went to bed and woke up. I also recorded my mood. I rated, on a scale from zero to ten, how happy, alert, mellow, and theistic I felt.
I was expecting to believe in God less on days in which I was in a bad mood. I was thinking I would feel grumpy, and this would make me doubt God's existence, in which case my doubt would be illegitimate; the other possibility was that I would doubt God's existence, and that would put me in a bad mood.
I was surprised and liberated when I looked over a few weeks of data, and realized that there wasn't a meaningful correlation between mood and theism. I have a flakey problem with anxiety that comes and goes, independent of my life circumstances, and I go back and forth on how I feel about belief in God; these two things are independent. It's good to know this. Since then, I stopped telling myself that I feel anxiety simply because I don't believe in God, and I no longer tell myself that my unbelief is a mere artifact of my condition. Putting a feather in my cap might cheer me up, but it won't make me believe, and I need not force myself to believe something that I find unreasonable just to control my mood.
The problem of knowing God is different from any other knowledge problem because you can't control for God. That is, we don't have access to two universes, one with God, and one without, that we could compare what it would be like to be in one instead of the other, and know for sure what sorts of things prove that God is there. Some people look at poverty and use that as proof that God isn't real, and some people look at the compassion shown to and among the poor, and use that as proof that God is. However, without another universe to compare with, we can't honestly connect the dots between the state of our universe and whether God is real.
One can control for God a little bit, though, if one believes that God can be experienced personally, rather than only seen in nature. I used to think that experiences in meditative prayer were valid reasons to believe that God is there, until I started doing simple breath meditation. What I felt in meditative prayer wasn't any different from what I felt in breath meditation, so it's reasonable to explain those experiences as resulting from the repetition, the quiet, and the focus on breath, these things are the shared between the two practices.
(What I found in meditative prayer was superficial, it was what I wanted to find. I don't think this disqualifies meditative prayer from being useful and special; I don't know of anyone who promises that meditative prayer is particularly useful unless it's practiced consistently for a long time. I'll keep trying, to see if there's something else.)
Maybe you could compare how you feel while singing with a group of friends with how you feel singing worship songs in church on Sunday morning. Compare how you feel reading a good book, The House at Pooh Corner or Thus Spoke Zarathustra, with the feeling you get while reading the Bible. Look for the times when you didn't pray and you should have, and things still turned out pretty well.
It would be a needless loss to live your life thinking that God is there, if he isn't, if your belief was only grounded in how you feel singing worshipful songs; you've at least missed many opportunities for fun in sing-a-longs on car trips, you might find those times just as significant. It would also be a needless loss if you believe in God, but for vague and subjective reasons, and that satisfied you, if God is real and has better things to show you.