God, The Bible and Circularity

A "classic" example of circular reasoning found repeatedly, and with slight variations, in assorted textbooks on informal logic, reads like this: "God exists because the Bible says so, and we know that what the Bible says is true because it is The Revealed Word of God. " I What exactly is wrong with this argument? Are there logical gaps in the inference drawn from the premisses to the conclusion which warrant the judgement, "the conclusion does not follow"? Interestingly enough, any argument which begs the question, including any circular argument, is always deductively valid. The reason for this is clear. "A conclusion cannot fail to follow from a set of premisses which include it. "2 The negative answer to the latter question can be illustrated by first casting our "classic" fallacious argument into an abbreviated dialectical form and then abstracting the premisses and conclusion from it. Perhaps this is how the 'howler' was first committed.