In the course of discussing Genesis 22, wherein God commands Abraham to make a burnt sacrifice of Isaac, and Abraham is going to obey but at the last second God says Never mind, I was only testing you, you passed the test, we're cool, Søren Kierkegaard came up, and how, in his book Frygt og Bævenhe asserted that God's commandment that Abraham kill Isaac and offer him as a sacrifice, and Abraham's decision to comply, cannot be understood rationally. I disagree. The story itself, like all religious stories, is irrational. But like all religious stories and precepts it can be understood rationally, but only from an atheist point of view. Abraham might never have existed, this story of the human sacrifice which almost was clearly sends the message that God must be obeyed, always and unquestioningly. The tale also seems to point to a time in the ancestry of the people telling it when a transition was made from human sacrifice to animal sacrifice. This is subject matter for anthropology, not theology. Kierkegaard was brilliant, except when he was Christian, and vice-versa. Thank goodness in a lot of his writing the voodoo does not interfere with the clarity of thought. If only he could've stopped fearfully trembling before That Which Is Not. The story of Abraham can be understood rationally, but not while sharing Abraham's irrational belief in a big meanie in the sky who runs the universe.
I don't think religious beliefs are defensible. That sounds very harsh, but I don't think we should tiptoe around such issues. Thousands of years' worth of tiptoeing has been more than enough. Kierkegaard is much less irrational then many other theologians who claim that belief is rational and produce reams of the most appalling nonsense to buttress that claim, but not quite as rational as his many atheist fans who decline to accept ancient irrationalities.
Of course, it sometimes benefits people -- real, non-imaginary people -- when their fellow humans fear and tremble before an unreal deity. It distracts them from fear and loathing which would make sense -- fear and loathing of powerful rulers who claim to act in the public interest but do not, for example. (Of course, it's much more admirable to stand up to tyrants than to tremble before them, but it's also heroic, and let's face it, the vast majority of people simply aren't heroes. Maybe that sounds harsh too, but it's plainly true.) It's no coincidence that the worst tyrants appear to be very religious, whether they actually are or merely find it useful to have their subjects distracted by an imaginary tyranny. I don't doubt that many rulers sincerely believe in God, when they're told from infancy that they have been selected by God to rule -- for the good of all, of course. Most of us are susceptible to flattery, and the temptation to believe it grows as the flattery grows more constant and extreme, and what could be more flattering than being told your entire life that God has chosen you to be one of the leaders of His creation?
Sincere or cynical, promotion of religion is very practical for rulers. Most of us don't have such an excuse for holding on to religious belief.