@Diogenes phil,
Depends on the perspective of your question. It also depends on your definition of what a God is. In relation to the physical world, (I'm not familiar of a philosophical term used to describe the physical realm - that what can be observed and investigated), GOD doesn't have to exist. Think about Darwinism, the theory works without a need for GOD. Although from a cultural perspective, the existence of GOD in religion, for example, is required. Therefore, for faith to work, in a modern religious sense, religion requires an icon which represents the creation of life, ie. GOD. Thus in some perspectives you need GOD and in others, where laws or theories apply, then GOD has to exist.
Hypothetically, what if someone proved that there is no such thing as GOD - would you be content knowing that life is just a cycle of reproducing, eating, other things in between and finally, dying?