I'd argue that this isn't an accurate representation of the circumstance. It's not just as likely that a god exists as it is that one doesn't. You're correct in suggesting that the actuality of a god can not be disproved but the merit of the god hypothesis can be examined and determinations can be made as to the probabilities of its accuracy.
The only way we can establish the probability of the existence of a God is if we claim that God has some effect on the world in which we live, that we could detect. And indeed some religions make such a claim, and can thus be argued with on those grounds.
However, most religions claim that God is the source of ALL that exists, and that the nature of existence itself is the "will of God". If this is the case, then there is no possible backdrop against which the effect of God could be quantified, because EVERYTHING is the effect of God.
Once our definition of "God" includes the infinite, our ability to quantify the effect of God's existence (so as to establish probability of that existence) is lost to us. And this is why I say that the probability that God exists is exactly the same as the probability that God does not exist: because such probability cannot possibly be established once we define God's existence as infinite, which almost all people do, these days.
Supernatural claims are a dime a dozen and if science were able to examine, test, and retest just one of them and subsequently come to the determination that it was legitimate, the merit of the god hypothesis would benefit tremendously. But the fact remains that not a single purported supernatural events has ever been substantiated even though James Randi and his scientist colleagues have a million dollars waiting for the first person who can present to them a supernatural phenomenon that can be studied, tested and substantiated. Needless to say, the money is still up for grabs.
Yes, you can successfully argue against claims of "supernatural phenomena" using reasoned probability. But this argument does nothing to support or deny the existence of "God". You can rattle a few religious believers, by poking at their irrational superstitions regarding God and their belief that God performs "supernatural" feats, but all you've done is argue against a minor aspect of religious idealizations of God. You will have done nothing to actually discredit the assertion that God exists.
To successfully argue that God does not perform "supernatural" feats is not the same as successfully arguing that God does not exist. These are two separate claims.
I believe in the existence of a "God", but I do not believe that God performs supernatural feats, defying physical laws and altering the course or flow of existence. And in fact it's exactly because God does not meddle in the flow of existence that we can't "detect God", and therefor can't quantify God's effect and establish a probability for God's existence. God IS the source and flow of all existence. So it would be irrational for God to meddle with that flow. To do so would be God countermanding Itself.
The scale isn't balanced. Evidence in favor for the god hypothesis is limited to the subjective experience of the individual.
No it's not. The "evidence" for my God-concept is all of existence.
Including science. Existence itself is the "body of God". The way existence expresses itself is "God's nature/will" and my part in this divine expression is my "relationship" with God. It don't get more "real" then that.