Clearly, though, in neither passage is Jesus condemning the practice of animal sacrifice.
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Well He was a Nazarene....and although the Jews were permitted to continue these pagan rituals it was never ordained by God. And not too long afterwards, Judas would sell Jesus to the Romans to be sacrificed.
When one looks up the Greek interpretation of den of robbers it is interpreted differently than just a den of theives. Lestai is more aptly described as brigands or violent ones. Which suggests to some scholars that commerce taking place in the temple wasn't the problem that Jesus was addressing when he called it a den of robbers.
Jerimiah also suggests that the temple provided security for those purposely violating the covenant and Jesus thought the temple was becoming a centre of resistance to the nations...rather than a city on the hill that shines its light over every nation.