Does the Toulmin Model negate the claim of God's existence (and/or religious miracles) in rational terms?

Ok, i hate to set up a whole new post (especially one with such an outlandishly long title) when we've got so many interesting conversations swirling around the blogosphere, but I, like always, wanted to stir up some controversy. In religious debates I've always tended to take a, as my mom puts it, "preach from your soapbox" kind of Christopher Hitchens approach. But, as the Toulmin model has taught me, this just isolates the audience even further. But I'm getting off track. The point is...

Take for example the simple claim "God exists and is omnipresent, omnipotent, and omniscient." We need some sort of grounds to back this statement up. A purely fact based argument is simply out of the question seeing as we have no verifiable data, no scientific evidence, or substantial references to back it up. An opinion-based grounds (not the same as opinionated) is plausible, but would be rather flimsy, given the need for opinions to be backed up with facts, and are in fact interpretations of fact. And case examples do not work because even if the audience shares a mutual understanding of God as you do, this assertion is only speculative, and examples dealing with reality are vastly more convincing than hypothetical ones.

So a believers argument is simply stalled in the early stages of development. But, we could examine the flaws in any case claiming divine dictatorship in more explicit detail in later stages of the method. I'm sure this is getting tedious so I'll pose one example.

One might claim God's existence through any set of "miracles" witnessed on the planet. I'll forgo the obvious tawdriness and ambivalence of said miracles (when a football player makes an astounding athletic play he thanks God for "blessing him in His infinite grace", but when an infant dies just hours after being born from some sort of painful deformity, God is either not mentioned at all or "it was just in God's plan to take the child"), and focus on the fact that causation does not equal correlation. It never ceases to amaze me that the major religious factions scoff at superstition, when their own beliefs are laden with the same inaccuracies. Because one prays for rain and subsequently it rains the next day does not mean that God picked up your prayer on one of His many ears. It simply means that the meteorological conditions of this cooling Earth have produced precipitation in your region. The cause does not match the effect.

Okay I'm done ranting. Do with this what you will. If I am sounding snobbish or preachy, please do let me know.

(Taylor Burke)