Thanks for the reply. I think you and my 17 year old DD would get on like a house on fire. She's mad for anything HP and spends hours working out the complicated inter-connectedness between plot lines and people and places, and writing (quite good) Potter fanfic 
But this is only worth doing if you believe that the bible is true and worth investigating in the first place.
A good point, of course, though there are countless biblical scholars who don't think it's true but do think it's worth investigating in terms of it being an interesting historical documents which says something about various cultures through the ancient world. But that's off point; I know what you're saying. How can I invest so much time in study of these texts if there isn't enough evidence for them to be true - or more pertinently perhaps, how can I live my life by these texts? (Given that, as you said, it's quite possible to invest hours of time in something which interests us).
You ask me about evidence. Why do I believe it's true? I'm certain you'll have heard all the arguments from cosmology, ontology, anthropology, morality etc etc, and realise they are not enough for you. I find that they point towards a God, but that could be any God (apart from the moral and probably ontological/anthropological arguments which go rather deeper into the possible nature of that possible God) - so, instead of hashing them all out, which would take some time and be unbearably tedious for those reading, I'll come to the central point of belief for me, and that's Jesus.
We live in a world where there are countless claims to authentic spiritual experience, which is why you ask these questions: I'm simply laying claim to another one of the many. When you hear so many differing accounts, it's not surprising that you remain skeptical and discount the lot. I probably would, too. So how can I know what is actually rooted in reality? That my 'experiences' are authentic and not simply heightened emotion/the power of suggestion?
For me, the key is Jesus, because in addition to my experience of God is this person in human history - and because of this person, Christianity can be investigated.
It's impossible to explain the rise and actions of the early church if events recorded in the bible didn't actually happen. Very few peer-reviewed scholars doubt the existence of Jesus. Jesus has left a massive print on history - an unknown carpenter, murdered ignobly in shame. Any movement started by someone like that would be quickly curtailed at that moment.
Obviously, the key question comes back to the resurrection. It's an outrageous claim, flying right in the face of what we know of the natural world. A claim which the ancient Graeco-Roman world would have jeered at and completely discounted as much as we do today. Their worldview - and that of the Jews also - would have rejected resurrection as impossible and also undesirable. Some Greeks and other eastern faith systems had some concept of a god in human form, but it would have been absolute anathema to Jews, believing as they did in the one transcendent God.
Many other messianic pretenders at the time died in a similar way, but none claimed resurrection. It's a unique claim which fired a body of people into radical and subversive action, a unique, embarassing story. The earliest believers must have come to their belief despite it rather than because of a formed idea about how it 'should' be - it simply wouldn't have been accepted as a notion, let alone carried through as a massive deception involving stolen bodies and unfounded claims.
The huge explosion of Christianity was unprecedented. These new followers of Christ adopted this brand new belief unlike anything in the ancient world (and don't get me going on the Mithraism 'comparisons'...
) Usually, in the adoption of faith systems, it would take decades to form a developed understanding of practice. This took a very few years, as some of the Pauline letters show, and some extra-biblical evidence (yeah, yeah, I know, let's not get going on it)
I know all the refutations for all of this (and there is so, so much more, but really don't want to go on), but despite them and through them it still makes sense to me, and more than that, it breathes life to me, and to countless millions through history who have encountered Jesus afresh. Jesus is who I look at to make sense of God.
But how do you know that the experiences you have are real and even if they were, how do you know they mean god. I strongly suspect that you have bad reasons for believing.
Yes, I understand why you would think that about believing something so incredibly out-there. How could anyone? And how could anyone know an experience means God?
I think, for me, part of it is the changes I see in my life when I've encountered God in different ways. There's a passage in Galatians which talks about the fruit of the spirit, or the result of following Jesus, things like patience, kindness, gentleness etc. My experience has been that those things have increased in me and become even more important. This does NOT equate to me saying that folk without belief can't show these characteristics: far, far from it - just that in my own life, these things have further formed through coming closer to God. I've been changed. So while the experiences themselves are unquanitifiable and unmeasurable, the result of them are less so - though of course you could say that was my own drive and longing to be more like that. I can only tell of my experience - I know it's never going to be enough. But it is for me - immeasurably enough and more.
It's peace too - a peace so deep I've never found in anything else. I don't want to sound too cliched, but I can't not mention it. It's just there. It's soul-rest.