
Christianity (being descended? from Judaism) simply kept the concept of being able to dump sins on someone / something else by using the figure of Jesus......I guess as the world moved forward into the dark ages that a Goat just looked silly

Which does kinda explain how the Satan figure came to be represented by a Goat - it's simply discrediting the old religion. and giving an excuse to kill the practioners.
And I didn't even make all that up - someone beat me to it
