One thing I often come across in researching historical pagan religions is the frequent use of animal, and occasionally human, sacrifices. For instance, sacrifice appears to have been the primary method of worship during a large part of ancient Greek history. To give a specific example, Hecate was strongly associated with dogs and dogs were occasionally sacrificed to her. Within Germanic paganism, human and animal sacrifices seem to have been a fairly frequent practice. Accounts of the major temple that existed in Uppsala in modern day Sweden were particularly gruesome as the sacrifices would be left to hang and rot in the trees surrounding the temple such that the trees around the area were completely covered in the rotting corpses of animals and, potentially, humans. Of the Celts it is hard to say for sure what many of their specific beliefs and practices were since much of what we know about Celtic practices, particularly in continental Europe, is considered rather dubious since much of it was written by the Romans and others who were often at war with the Celts and portrayed them in a negative light for propaganda purposes. Still, it's almost certain that druids officiated over some sort of sacrifices, though scholars seem torn about whether or not this included humans.
This is one aspect of paganism that I have a little bit of a hard time figuring out. Obviously, the vast majority of pagans in the modern world do not engage in any kind of murder or animal cruelty, and those that do are usually found to be mentally ill and drawn to these practices for that reason rather than for any particular religious reasons. What I'm curious about is how modern pagans reconcile their current religious practices with historical evidence of human and animal sacrifices, though.
I mean, I could reconcile some of it to an extent. For example, most people in the ancient world either worked in agriculture or were closely tied to agriculture. If we take the meaning of the word sacrifice to mean the giving up of something meaningful to one's self to a deity, it makes a little more sense. If you were a shepherd, your flock was your life and sacrificing a sheep to a god would be somewhat equivalent to someone in the modern world giving up a week's pay in order to donate it to some cause tied to the worship of a particular deity. That still doesn't help to justify the sacrificial practices amongst the ancient Greeks, the Germanic peoples, and others for whom sacrifice appears to have played a fundamental role in their worship. I'm just kind of curious to hear people's thoughts on this and how they reconcile their modern beliefs and practices with the historical practices.
Where I personally stand on the matter currently is that most pagan religions appear to have been a fundamentally different than religions like Judaism which codified specific laws and guidelines concerning the proper manner of worship in a way that explicitly asserted the unchanging and unalterable nature of these laws and guidelines. As such, practices in the ancient world can, and did, change over time as people progressively came to experience deeper aspects of the divine which altered the ways in which they thought it proper to honer and connect with their deities. Probably the most famous example would be Hinduism which still considers the ancient Vedic texts to be sacred even though they contain references to animal sacrifices. This, of course, seems quite strange since most modern Hindus are so opposed to killing animals that most are fairly strictly vegetarian and don't even accept the slaughter of animals for the purpose of using them as food. Many Hindus would probably insist that there isn't a disconnect between their modern beliefs and the beliefs contained in the Vedic texts, but that they have progressed to a deeper spiritual understanding of divinity and ways to connect with it. On the other hand, I suppose it's important to keep in mind that there are still some very conservative movements within Hinduism that still practice animal sacrifices on certain occasions.
Anyway, to avoid rambling on much further, I suppose my current belief is that our knowledge of the divine, just like our knowledge of more mundane things like physics or algebra, is constantly growing and evolving. As such, I suppose there isn't a disconnect there since we're not throwing out primitive ideas and replacing them with new ideas, but simply expanding upon the primitive ideas to grow into a deeper understanding of the topic. I'm not really sure how much sense that makes, but you probably know what I mean. Regardless, I would be keenly interested in hearing other people's thoughts are on this topic. Assuming, that is, that I haven't completely put you to sleep already by my massive wall of text.