No. It is, however, suspicious - what led you to hold such a conveniently untestable belief? What do you think you know, and how do you think you know it?

To be unable to produce an experiential distinction from a belief, is usually a bad sign - but it does not always prove that the belief is meaningless. A great many untestable beliefs are not meaningless; they are meaningful, just almost certainly false: They talk about general concepts already linked to experience, like Suns and chocolate cake, and general frameworks for combining them, like space and time. New instances of the concepts are asserted to be arranged in such a way as to produce no new experiences (chocolate cake suddenly forms in the center of the Sun, then dissolves). But without that specific supporting evidence, the prior probability is likely to come out pretty damn small - at least if the untestable statement is at all exceptional.