I would read this one first. It explains the WHY better than other texts which seems to be your primary hurdle. If you can't find it I can upload it to /pdfs/ for you.
Why this one and not other books like "on being a pagan" by benoist first? Because I think this explains genuine belief and actually feeling the gods through you in ritual and practice as opposed to more humanistic, aesthetic or "rational" texts that simply amount to "us=european, these practices and gods=european, other practices and gods!=european, so lets act out this religion for a better fit". Which is true, mind you, but the difference between knowing and liking the idea and actually believing in it or truly feeling it is another matter.
Before reading this title I kind of bounced around as a "heathen" who liked the idea but didn't actually "feel it", and I wish it had been one of my first books instead of certain other ones. (Assuming you actually know your mythology and the names of the gods and the basic framework, otherwise you should go read those first).