Marty, the human suthors of sacred scripture sometimes put outrageous words into God's mouth  not to lie but simply because that is the level of development at which they are .
When , 2000 years later  we read them we can go deeply into meaning .
So these " babies " who are to be slaughtered are one's own desires , ideas , behavior etc. which are keeping us from living a life of gospel values and claiming the place in which Our Heavenly Father wants us to live . 
Meaning,  meaning , meaning is in the message .