Behind existence? Yes, I believe that. I think his existence is the big "why". Plus I'm not a big fan of spagetti. Perhaps a pizza monster though. Or better yet, a pizza kaiju. That would be fantastic.
As to macro evolution and carbon dating, I really don't have any way to debate you. It's not something I know a lot about, so I'll think I'll have to bow out on that one here.
For the no practical function, I'm not very sure where I brought that up. It makes perfect sense for things to have useless traits in with the good. I got my moms good looks, but I'm only 5'6'' so it's not nearly as useful as it could be
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And as for the unforgivable sin, that's right.