The essay "Theology and Falsification" by the British philosopher Antony Flew is, as the author is modest enough to admit, "probably the most widely read philosophical publication of the second half of the twentieth century." It is around a thousand words long and raises the objection that God-talk is meaningless. When someone says, for example, "God is love," it appears that something is being asserted. But what, exactly? If something is asserted, then something must be denied ("if p, then not the opposite of p"), which suggests that the assertion could theoretically be proven false. Regarding "God is love," what is being denied? What event, or proposition, if shown to be true, would disprove the "assertion"? We are told that "God is love" is not disproven by cancer in young children, "because His love isn't a human love," etc., etc. Okay, what would disprove it? If there is nothing that, if true, would cause the assertion to be withdrawn, then nothing is actually being asserted. It's just empty happy talk, a fake assertion, the expression at most of a mere "picture preference." That's the argument of the very brief essay.
To me it seems very cogent and generally applicable. The success of Clinton's economic program, despite the Republicans' dire predictions of what would be wrought, did not shake their confidence in their economic views. What would? The medical literature does not dissuade devotees of certain "alternative treatments." Is there anything that could? What would it take to turn practitioners of occult practices into materialists on the ground that the former had been proven to be bunk? If the answer to all these questions is "nothing," then we don't have to take them very seriously. Whether or not they're right isn't an interesting question compared to why they believe as they do. The psychology of belief is a large field. Flew's phrase "picture preference" (which he borrows from another philosopher, John Wisdom)generally has a larger role than the merits of the particular case.