The reason that I said ‘a variation of the conjunction fallacy’ is that the standard conjunction fallacy that I know is about assigning probabilities to propositions rather than attending to them. (You might choose to attend to something with a fairly low probability, for example, if its expected consequences are significant enough to overcome this.) Nevertheless, to consider the possibility that Jehovah exists, you must consider the possibility that a god exists.
The reason that I said ‘a variation of the conjunction fallacy’ is that the standard conjunction fallacy that I know is about assigning probabilities to propositions rather than attending to them. (You might choose to attend to something with a fairly low probability, for example, if its expected consequences are significant enough to overcome this.) Nevertheless, to consider the possibility that Jehovah exists, you must consider the possibility that a god exists.