Mrs. M called me the other day and asked the above question? She said God teaches us to love everybody, even our enemy, so He must love the devil. I wasn't quite prepared to answer this question, but I felt sure she was wrong and there was some contradiction involved.
The web provided several items on the subject, mostly from Protestants--even Billy Graham stated that God hated the devil. The Catholic Encyclopedia article on the devil did not answer the question, so it appeared to me that the answer was a matter of theological speculation. [Suarez, De Angelis was referenced as being the prime Catholic resource on the angels and Satan.]
So armed with a few printouts of interest, I took three grandchildren with me to visit Mrs. M in the nursing home. On the way, I explained to the 12-, 10-, and 3-year olds the question that Mrs. M had asked. The 10-year old immediately said, "But how can God hate his own creation?" What a question! The Bible is clear that the devil is our adversary and we must oppose him, but does God hate the devil with some divine perfection? My own answer follows, subject to immediate revision should the Church have already addressed this issue.
God and the devil exist outside of the dimension of time in our universe: God as creator of time and all else that exists, and the devil as a spiritual being created by God. God loves the devil because God loves His own handiwork. However, the devil has an unrestricted free will because he is not tempted by anything external to his own nature. God hates the devil for what the devil has freely chosen to become.
In contrast to our sins which can be forgiven in this world, the devil's sin is unforgivable. Even the sins of our enemies can be forgiven. Moreover, Christians are required to be part of God's plan to give His love to our enemies so they are not eternally damned. Not so for our enemy the devil. Once the devil sinned, he sinned forever.
A basic principle of Christianity is "Mercy in this world; justice in the next." God is unmerciful outside of time, because then His mercy would contradict His justice--and God is NOT contradictory! The devil's sin is unforgivable because he cannot change; change requires intelligent beings to exist within time.
When Satan rebelled, God may have constrained the devil to the straitjacket of time to suffer in hell and to tempt man, yet not to know the future. God foresaw the devil's arrogance, yet the devil's pride and his temptations of man are part of God's plan in time.