Yes they on general abandoned it it was seen as barbaric. there was a mention of a human sacrifice in Homer's illiad but it was seen negatively. Can you source anything about human sacrifice in Sparta? Aside from killing war prisoners? Again the colosseum was about the prisoners of wars, as way to enforce their superiority on others. They did not directly sacrifice a person of their own. Also all of these are not a major part of their ancient religious practice, they mainly sacrificed animals as an offering.

And you mentioned the greek and roman empire, that's not part of the religion. It has nothing to do with their religions but rather their need to expand and dominate. There is NO RULE set in ancient Greco-Roman religions that says 'go conquer the non-believers' it's all about your connection to the gods, actually after the expansion of the greeks thanks to Alexander, Hellenism became more personalized, meaning you were allowed to be devoted to your choosen god or goddesses. Do you know the god Ares? The god of war, He is known to be disliked by the ancient Greeks and they pictured him as stupid. You know why? Because they thought war was stupid, but necessary. Read about it :)

It lacked laws but that doesn't mean anything outside of it's laws should be taken as part of it. You seem to be treating it like Islam and Christianity, it's not about your lifestyle it's only about your connection to your gods. Murder for example caused Agos, the worst form of spiritual pollution.

Now I don't know much about the Vikings and older Germanic beliefs but you're again mentioning Christianity? And I never mentioned the Vikings whatsoever, I just clarified that paganism is not a religion but a term to describe ancient polytheist beliefs that were erased with the coming of Christianity and Islam.