You won't see that in Google's guidelines (and there's little evidence of any such number!).
If you read your pages as you prepare them, you'll know if the keyword limit has been exceeded, because the words will sound silly; if in doubt, get an honest friend to read them - or read them out loud.
I really don't think religion comes into it; and I don't even think ethics necessarily feature, either (that's entirely a matter of choice).
SEO, especially for Google is mostly reading the guidelines, and recognising that Google seeks to emulate the human experience. The rest is very largely common sense!
You do take my words very literally, but fair enough; let me rephrase: If they start telling people exactly what they have done wrong, their advice may be useful for spammers. They'd have to be crazy to even consider it.