First, you will find that the pantheon of gods and demigods found in ancient Greece, Rome, Norway, etc. were not really considered completely separate, individual gods, but were generally considered to simply be aspects of a single God. You will find, in many cases, that those called sun worshipers never considered the sun itself to be God, but rather a kind of window between heaven and earth, between the spiritual and the physical. And you will often find that blood sacrifice was not as common as the Christian writers want you to believe and, when it did occur, was often not considered to be a sacrifice to God, but one to appease evil demons, the only type of spiritual being that would want blood sacrifice or could benefit from it.

    And the modern churches are not as different as they like to think they are. Solar symbols can be found in many churches including the monstrance that holds the host. And, while actual blood sacrifice doesn't take place, it does symbolically when the priest of minister turns bread into the flesh of Jesus and water or wine into His blood, and then the church member drink and eat the flesh and blood of Jesus. Symbolic cannibalism.

    There are books available that tell the truth about the ancient religions and how the early Christians, particularly the followers of Paul, copied much from those pagan faiths in order to make the new faith seem familiar and acceptable, and if you want to know more, you should read them.