There is something pleasing to a mystic in such a land of mirrors. For a mystic is one who holds that two worlds are better than one. In the highest sense indeed, all thought is reflection. ...Man alone is able to see his own thought double, as a drunkard sees a lamp-post. Man alone is able to see his own thought upside down as one sees a house in a puddle. This duplication of mentality, as in a mirror, is the inmost thing of human philosophy.
– Manalive, G.K. Chesterton
It's been said before in other ways, but – as usual – I feel Chesterton says it best.
The fact that we are only creature on Earth with self-awareness is fascinating in and of itself (especially because there is no real practical use for it – it allows us to act against logic and our survival instincts). But I think it's also a clue about the nature of the multiple worlds we inhabit daily: we are body and spirit, mind and soul, driven by both reason and impulse – and we overlap everywhere. Rationalism itself requires faith; intiution makes sense of a illogical situation; art speaks in a wordless language that is nevertheless universally understood.
When people ask me why I believe in God – and particularly why I believe in Christ – I am usually assaulted by too many possible responses to pick just one. But I think the key thing is this: that God's existence and Christ's reality account for the whole of the human being. And there is no other philosophy, worldview, or religion I have encountered that does this (IMO). Some of them do a compelling and insightful job of addressing certain aspects of humanity, but they leave other things out (or claim those other things don't exist). Only Christ accounts for all of it – engages the whole of the human being without leaving any part of it unspoken for.