I read this, took a shower and can now share my own shower thoughts.

Imagine explaining all of this to a person asking you why you're unavailable on a Sunday. It's much easier to just say "my god says so". Depending on the person, it also often gives much higher chances of them respecting your way of life.

I embrace the Christian concept of the seventh day of the week free from work, having arrived here in a completely non-religious way. It's one of the things that made me convinced that there is some value in religion, despite all the corruption and misguided dogmatism on the surface.