Augustus
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Yes, it would be both logical and rational to reject any position for which there is no objective evidence. Your happiness has no bearing on reality.
It has no bearing on objective reality no, but why is it highly important to be objectively correct? If you want to build a plane or a submarine you need to be correct to a high degree or you will die, why does it actually matter to be objectively correct on an issue such as religion?
What would be rational about an individual living a less fulfilling and beneficial life simply for the ability to be objectively correct on a particular issue of little importance? Seems highly irrational to me.
So where do you draw the line between the rational and the irrational. We agree that YEC is irrational, that scriptural literalism is irrational, well ... let's turn the question around, would you list a few things exclusive to that, "epistemologically shaky foundation" that are, in fact, perfectly rational, and that we might agree to as we do YEC and literalism?
You do not believe in God, which mean you believe that religions are human constructs. I don't know if you subscribe to the perspective that religions were created by an elite to control the masses, or that religions evolved from the masses and were later co-opted (and potentially refined) by elites. For me, the latter is a much more tenable position.
With any idea, theory, etc. the longer it has survived with popularity, the more likely it has genuine merit. This doesn't mean it is flawless or doesn't contain any errors or imperfections, but standing the test of time is one of the best methods of evaluating something's merit.
Religion contains (at least) 2 'parts', the supernatural part and the ritual, rules, knowledge, wisdom and guidelines part. The supernatural part is the less important of the 2 and really serves as a foundation for the ritual, rules, knowledge, wisdom, guidelines part. There is no exact line to draw between the rational and irrational, but on a continuum, you are less rational the more you focus on the supernatural aspects and the less you focus on the 'real world' aspects.
So religions contain an aggregation of knowledge drawn from the masses over thousands of years that has survived for thousands more. This is very substantial evidence that at least a significant portion of this knowledge benefits individuals and society and one can be considered rational for believing in it.
Look at many guidelines, avarice is hated, usury is forbidden, do not covet what others have, be thankful for what you have, forgive others their mistakes. We can easily find some modern 'objective' evidence for the benefits of these things, also many religious rituals, etc.
If we look at modern problems such as the debt crisis, inequality, shallow consumerism, depression and social isolation, there exist provisions in religion that would help mitigate these.
Each generation underrestimates the chance that their new ideas may be incorrect and harmful, which is why people need to remember lessons from the pasts. Religion has proved the best method of doing this, not the only way, but by far the most effective and successful. It also reminds humans that they are not omnipotent, and much of their life is 'in the lap of the Gods', something that many modern people seem to forget also.