The Greatest Conceivable President

(1) Let Obama df= the president the greater than which cannot be conceived.
(2) A being which exists in the mind and in reality is greater than if it existed in the mind and not reality.
(3) Obama exists in the mind and not in reality. (assumed for indirect proof)
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(4) Therefore, a candidate for president is conceivable which is greater than X. (from 2 and 3)
(5) Therefore, a candidate for president is conceivable which is greater than the president the greater than which cannot be conceived. (from 1 and 4)
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(6) Therefore, Obama either exists neither in mind or in reality of Obama exists in both. (from 1-5 by indirect proof)

Comment: Even if we accept (2), the argument fails because the inference from 2 and 3 to 4 and again to five is false. The valid entailment is actually:

(5') Therefore, a being is conceivable which is greater than the president the greater than which cannot be conceived.

which is not absurd and this does not lead to an indirect proof of the existence of Obama, much less that this or that empirical candidate is the Obama candidate.

However, in the case of letting God be the greatest conceivable being, the inference does work and it a least shows that the concept of God necessarily involves necessary existence as if existence were a great making property of God, even if it fails to show that God actually does exist. Further, if there is any recognition of a hierarchy of good things that goes beyond the empirical facts about the world, as seems often to be the case, that would be explained by the existence of God as the greatest conceivable being, so it is at least epistemically possible that God exists. So given the conceivability and epistemic possibility of God, a trusting belief in God is a rationally live option for someone who is brave enough to risk seeking God rather than just living life.

However, it is not clear that it is conceivable or epistemically possible for any candidate to be the Obama. As far as I know, not one of them in the 2008 USA presidential race has claimed to be God yet. So it still seems to me that religion is more a rational choice than Obamism.