Tricky one... I couldn't really think of any books that had *changed* my life, only those that had affected my life.
but after a bit of thinking...
"Www.Here-I-Am" by R. Stannard- a children's book about a boy who one day finds that God is communicating with him through his computer. They talk about many things- Jesus, good vs evil, sin, etc. At the time I read this, I was about 12. I was a Christian because I had been brought up as one (my parents were atheists, but most other people in my immediate surroundings were die-hard Christians). I went to church every Sunday, alone or with my older cousin, I prayed every night, stayed away from "sin", but I didn't feel "saved", it wasn't real to me, I longed for the feeling of spiritual contentment but however hard I prayed, nothing happened. I used to lie awake at night and cry because I was scared that I would burn in hell because I wasn't truly "saved" (ok, looking back I can only laugh at this, but I was terrified at the time!!!). I read this book, and the God in the book was based on the Christian God, but a modern, friendlier God (with a much better sense of humour!). I guess the aim of the book was to open up your mind, in the end was a list of questions that God had left the boy with in the end, and you were supposed to answer them for yourself. Can't remember any of them, but they were basically supposed to make you think about what kind of God YOU believed in.
That book I can say truly changed my life, although I probably hadn't thought about it for years until I started replying to this thread. It helped me overcome my indoctrination by Christianity, and put me on the path to other religions like Wicca- which isn't really my "thing" anymore, but it was fun while it lasted. All my religious and spiritual beliefs have faded now, and that's a real shame. But I like to think of this only as a temporary passing phase, hopefully I'll believe in something again, one day- I remember the time when I was into Wicca the most and it was a religion which made me so happy with who I was and the life I was living- unlike Christianity, which did the exact opposite for me.
Another book which has had an impact on me is "Sun Signs" by Linda Goodman. I'm into astrology but generally Sun sign descriptions don't give me that much, they're both too broad and too limiting, and too generalised (as opposed to taking into account all the planets, aspects, etc when interpreting someone's chart), but Linda Goodman is something else... That book is special, it's my astrology Bible. From reading my sun and ascendant sign descriptions in that book, I've learnt much about myself, and also understand other people better, whether they are potential love interests, friends or family members. And that is *not* something that I can say about any other sun-sign based astrology book I've read. But I guess what I like most about it is that it's written so beautifully. Even if I didn't believe in astrology, I'd read it for entertainment value only, because she sure does have a way with words.
Her "Star Signs" book changed my life a little, too. I read it a year ago, and after I was through with it, it all seemed too far-fetched, and I haven't re-read it since for that reason. But reading the book was a magical experience, for me, I didn't put it down and stayed up the whole night reading it. One of the few memories I have of being completely happy, even ecstatic, during that period in my life.
other books that deserve honourable mention:
one hundred years of solitude... this book is still changing me, slowly, silently
trainspotting, porno and glue by irvine welsh... Not sure they affected me in a good way, though. They gave me a glimpse of how low human beings can actually go, and I was disturbed by some parts of these books. Still, there's a lot of humour in them too, thankfully.
And there.. can't think of any more. used to be a complete bookworm when I was younger but this year I've read maybe 5 books in total. Gotta get me to a library, quick!