This argument is not circular; it is self-contradictory. It starts with a premise: that nothing exists that is not caused. From this, it somehow reaches a conclusion: that there is at least one thing that exists but is not caused (which, for some undisclosed reason, it refers to as god) and then goes on to ascribe to this one or more uncaused things a great number of attributes that are pure invention.
To put this in more formal logical terms; Premise: The set of uncaused entities is empty (has no members); Conclusion: The set of uncaused entities has at least one member. This stream of logic is very common and popular (and generally considered valid) within that branch of logic that has been named Theology.
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