As for the difference between assimilation and substitution, in this case I'd say it's paper thin.
Could you qualify why it's paper thin? is it simply paper thing because it servers your argument better to categorize it as such?
besides which, we're still TALKING about the Egyptians, the Greeks/Romans and their temples still stand (not to mention just about every official building of significance is based on their architecture) so in every appreciable, physical sense their cultures and religions survive, they simply aren't practised anymore.
Sooo... architecture = philosophical thinking now? again, could you be clear on how the physic's of building a structure and those principles being handed down is the same as human sacrifice to a goddess?
What do you think communion is? Bread=body, wine=blood, supplanting the previous rites of animal and human sacrafice through symbolic representation (Christ is "lamb of God" after all). Tithing IS sacrafice.
We were talking about HUMAN sacrifice, if you use your above way of interpreting it, then me not watching my favorite TV show is "sacrifice"