Satan was the real cause of Herod's actions. Ever since the Lord first prophesied that a man would bruise his head, satan has been looking for this "seed" of the woman (Genesis 3:15).
It appears that satan is able to know when the Lord is making a major move in the earth. In the days of Moses, satan moved Pharaoh to kill all the male children of the Israelite slaves, and here he gets Herod to kill all the male children in Bethlehem. No doubt he was trying to eliminate this "seed" who was going to bruise his head.
Now, we seeing children being slaughtered. This time it's through abortion. Our young are also being attacked in many different ways. Is it possible that satan thinks this is the generation that is to bring in the second return of the Lord? Is he desperately trying to hold off his doom by destroying this generation?
We need spiritual perception to recognize that just as in the days of Moses and Jesus, this slaughter of the innocent children is an indication of an even more important struggle in the spiritual realm. We might be the generation that sees the Lord come back. Praise the Lord!