It's self evidently true that where you are born and what culture you are raised has a massive part to play in what you would believe. If that wasn't true then there would be a homogeneous spread of beliefs, or lack of, across the world and cultural groupings. The percentage of Buddhists in Saudi Arabia or Brazil would be equal to that of Tibet for instance.
It's equally self evident that religious belief isn't an objective truth else we would of all pretty much decided on one truth by now.
But if you looking to get agreement from your ex-coreligionists then I'm afraid you will be waiting a long time

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