The "unholy" trinity

There are many mirrors which exist in this poem, however, one of the more powerful ones is the image of the "unholy" trinity.  While in heaven, God, the Son & the Holy Ghost exist in peace, Satan, Sin & Death have made war their home (naturally).  Sin is the creation of Satan (his daughter) and, after he rapes her, she is the mother of Death (who then rapes Sin creating the hell hounds).  

It is interesting that Satan tries to conquer Death when trying to open the gates.  It begs the comparison to the Son's sacrifice for mankind.  God allows his Son to die to save man, while Satan tries to kill his to corrupt man.  Additionally, Satan notices, "the likeness of a kingly crown" when he first observes Death (l. 673).  The Son is noted as the King of man in the next book, "Son both of God and man, / anointed universal King" (314/5).  Moreover, this idea of the trinity is reinforced in the description of the gates of Hell, "and thrice threefold the gates; three folds were brass, / three iron, three adamantine rock" (l. 645/6). 

The diction used when describing each trinity, the holy & unholy, differentiates the two.  When describing Sin & Death, Milton uses words such as foul, hideous, abhorred, black, dreadful & monster. When describing God & his Son, Milton uses words such as ambrosial, joy, radiant, bloom, summer & jubilee.  Thus, Milton shows the reader the extreme differences between the two.  While one is filled with hate, malice & aggression, the other is filled with love, joy & empathy.  And, eventually, the reader knows that the Son is going to kill Death (something Satan could not do); therefore, love kills hate.