Paul Tillich said that we should retire the word “God,” because it had become virtually meaningless. Meaningless because there is no consensus about what the word means. Wars have been fought, people have been slaughtered of the "right" and "wrong" definition of God. (It always makes me laugh when people say God is so transcendent that we can't know his mind, but then they DO know his mind about what he wants, what he expects, where he will send me when I die ...)
Tillich used expressions such as “Ultimate Concern,” “Ground of Being,” which pointed toward a concept of God as not a supernatural person somewhere “out there,” but as the ultimately unknowable direction in which all things point.
As Marcus Borg has articulated better than I could hope to, the God I reject is the god of supernatural theism, a “supernatural being somewhere out there.” The God that has become a selfish transaction for the unknowable afterlife. Christianity is not simply believing the right things so you can avoid eternal Hell Fire, it's about knowing and loving God, loving your fellow man, and as Jesus said in John's gospel that we "might have life, and have it more abundantly" (John 10:10). Borg's book, "Speaking Christian" has challenged me to rethink my opinion of God and of Christianity.
Unlike pantheism, which says the universe is God, God is the universe and that is all, I realized I'm a panentheist. Panentheist means all in God and God transcends everything. God is "the ground in which I live and move and have my being" (Acts 17:28). An imperfect analogy is of fish in a river. Fish (that would be us) live in a river, rely on the river for breathing, moving ... and yet the river is more than just the fish and flora and fauna, it flows into the Ocean, it nourishes life.
Life itself is a sacrament - simply by living our lives as genuine and authentic human beings we can meet God, not just know God, but meet him and know him completely.
This is also becoming the foundation of Progressive Christianity and the Emergent Church. I would be happily involved with these denominations because they allow for the intellectual honesty of searching, discovery, questioning and rejecting. And yet they acknowledge the traditions of Christianity and the beauty of the Bible - as a human creation. They acknowledge the beauty in and borrow ideas from other religions. They follow the truth, and still have an encounter with God.
I won't claim the title of Christian. The traditional, cultural understanding of that word means someone who believes things which for the sole purpose of going to heaven, of avoiding hell. I'm not that person, I don't just believe anything.
Watch this video from my favorite church (unfortunately it's in Springfield, IL or I would go every week) for a fuller understanding of my faith journey, which will continue until the day I die.