If marriage already existed before religion, why do some think it's pointless without religion?

If anything religion and churches came afterwards. Marriage have already existed before religion so why do some people think it's pointless without religion. It doesn't make sense. It started without religion. So they're actually contradicting themselves. So the ancient people's concept of marriage had no meaning?

The concept of marriage was there long before the development of organized religions. There have been marriage practices found in ancient civiliations like Mesopotamia, way back before even bibles existed. It started as a social institute, not a religious practice.

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They're basically saying it's meaningless to something that was already there before, that already existed.
If marriage already existed before religion, why do some think it's pointless without religion?
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