From Karen Armstrong’s A History of God: The 4,000-Year Quest of Judaism, Christianity and Islam:

Despite it’s otherworldliness, religion is highly pragmatic.  We shall see that it is far more important for a particular idea of God to work than for it to be logically or scientifically sound.  As soon as it ceases to be effective it will be changed – sometimes for something radically different.  This did not disturb most monotheists before our own day because they were quite clear that their ideas about God were not sacrosanct but could only be provisional.  They were entirely man-made – they could be nothing else – and quite separate from the indescribably Reality they symbolized.