  Here is how the argument works.  Imagine a pair of scales in which we are weighing evidence concerning theism and atheism.  Once side of the scales is labeled “Theism” and the other side is labeled “Hypothesis of Indifference.” Premise 3 says the scales are at first even.  Premise 2 says that there is nothing to put on the sale marked “Theism.” Premise 1 says that there is something to put in the scale marked “Hypothesis of Indifference.” The conclusion says that after we have weighed the evidence, the scales tip to the side labeled “Hypothesis of Indifference.”