So you have God who runs things and is beyond perfect, who suddenly decides to produce a son and make him next in line, not in terms of time, but in terms of importance in the kingdom. Satan, who thought he was the favorite son gets understandably jealous of this newborn. At least he has the sense to know that the problem is not the other kid, but the parent who brought him into the previously happy family. So he decides the only solution is to overthrow the parent. /