This thread seems to have gone up a notch. Mr. Semper’s thoughts have caught my interest. Very impressive!

Taking on the first position as to establishing the existence of God from the “Why?” question, it seems to me that this still does not necessarily establish the existence of God. Sure, the question “why” may stump the scientist on the nature of things, but I would still be a little weary on filling this gap with the answer – “God”.
Now with regards to EXISTENCE and PRESENCE, to add a little spice to the thought, do these (existence and presence) equate to REALITY?
Plato and Aristotle offered a very interesting insight – that existence is composed of Forms and Substance. If we think of something without a form, such as air, we have to consider particles before air can exist. If we think of forms without substance, it can be likened to thinking of a painting then removing the paint (substance), leaving us without any image.
But let's think of the relationship of reality and existence first. Are they equivalent? Does being real mean to exist? How do we test this?
Let's imagine us playing with two sets of Play-Dohs (Clay). Let's mold the first set into the shape of a dog and the second set into the shape of a tree. They have the same substance (clay) but the realities are different. So we may say that substance does not dictate reality. Now let's consider the form (shape). The dog has the shape of a dog which makes it a dog, the tree has the shape of a tree, which makes it a tree. A cube has the configurations of a cube which makes it a cube. But does the conception of a height, width, and length dictate the existence of the cube? Probably not, otherwise, the conception of a winged unicorn would establish it's existence. Existence has to have both Form and Substance, as the two philosophers shared with us.
So reality does not necessarily equate to existence. While we may say that our mental image of a cube is real, it doesn't necessarily mean that this cube that we imagine exists. It has to be combined with substance first before existence is established. Theists can say that their deities are real (however they conceptualize their deities to be), but their deities lack the substance to exist. Similarly, they can claim reality for an imagined 2 dimensional cube (I may lack the imagination for such but I'll give them the benefit of the doubt), but the existence of such is a different story.
So having said all these, the atheist cannot deny the reality of the theist’s God. But in the same token, the theist also cannot claim for their deity’s existence.
Now regarding Existence, Presence, and Effect.
Now since the theistic deity lacks the combination of form and substance, it’s existence may be questionable. However, I would agree with Semper and argue that it’s reality can be supported by Presence and Effect.
Bishop John Shelby Spong contends that God cannot be defined but can only be felt. Theologian Paul Tillich says that God is not an external being, but instead, the Ground of Being. God is an experience we feel from presence and effect – like love, for instance. This God-experience is like, as Bishop Spong described, “swimming in an eternal ocean of love”. When I try to describe this experience, words fail me; so I simply utter the name God. That name, to me, is no longer the name of a Supreme being, a miracle-worker, a magician, or a rescuer. That name is no longer a mere means but an end itself; and this end is love. With this in mind, I find myself realizing why I cannot see God but only know where God has been. From this, I realize that God is in me; God is a part of who I am, a part of who we are. God is love and another way I can think of in expressing God is by loving wastefully, by spreading love frivolously, by giving away love without stopping to count the cost.
If we look back at the Tsunami tragedy of 2004, we saw the way the way millions of people (regardless of religious or philosophical background) opened up their hearts to help the people who suffered. Same goes for the people who helped the ones who suffered in the Sept. 11 tragedy, from the hands of another group of fundamentalists living in "faith".
I think God (however we define God in our hearts) was revealed in the hearts of those who helped the victims. There was a convergence amongst Christians, non-Christians, religious, or secular groups, in the experience of love and compassion. There was one time I was watching CNN after the tragedy and I saw different people from different walks of life consoling one another and even putting their own lives on the line to rescue and recover victims. Right then and there I saw universal Truth in action. In tragic times like those, claims of proprietary to God does not matter. Whether you are a Christian, Muslim, religious, or secular, we get moved by the spirit of love for one and all. Could this spirit of love be God? Could this moving experience be God? I do not know. But I sure am glad that whatever it was, it was present.