@boagie,
There are a number of reasons why people believe in God.
Boagie is right - some do simply because the Bible directs them.
But this is not the only reason.
Others claim certain spiritual experiences reveal the truth to them, and many of these accounts are essentially identical to accounts about Buddhist meditation.
Others simply find God to be an effective metaphor, and effective way of understanding reality.
Often times, belief in God is like belief in Santa Claus. But to reduce
all belief in God to being so childish is to make some very negative assumptions about the intellectual capacity of very intelligent people.