I thorouhly and thoroughly believe that nothing is certain. God may or not exist; frankly, who cares? We live our everyday lives and apparently, nothing is going to change that. So who cares about God? If he/she/it exists (I will use he from now on, for the sole reason of simplicity) than he has done nothing more than give rise to life. And now that life exists, it is up to us to live it, with or without meaning. On a side note - is there a meaning to life? I used to be inclined to say that life is it's own purpose. These days I have come to peace with the fact that there is no meaning to life - and neither is there a need to be.
To come back to the existence and meaning of God, I believe that if he exists, he is definitely not where we should find the meaning for life. The meaning of life must be found in life itself, or there is to be none at all. In my opinion, Nietzsche was very correct when he decribed Christianity as a religion created by those who, in their ultimate despair, created a religion which condemned that which they lacked (wealth, happiness,...) and praised that which they did have (suffering, poverty,...). (BTW: Please don't flame me to death )