We need to turn from the attitude of being nice to those who are nice to us, or "I will only speak to those who are nice to me" mentality. Pastor pointed out that loving your enemy isn't about sappy sentimentalism or the false "Grecco-Roman" definition of love. Rather, love is "an act of the will accompanied by emotion leading to action of behalf of the object" (glad that pastor repeated that one a few times, as I had a hard time jotting that down completely. It's an excellent observation.)
As an example of this love, the people of Israel, while under the bondage of captivity to Babylon, were still instructed to serve their captors and pray for them, without having to "like" what had happened to them (e.g. sappy sentimentalism).
He made the point that our love of our enemies is motivated by our love for God. We love them, whether we feel like it or not. If you don't believe in a God of punishment, vengeance and a literal Hell, then all you can really do is hold a grudge. And I do believe in a literal Hell, but I differ on whether or not the punishment is eternal (I read an excellent book on the annihilationistview of hell and eternal punishment that I hope to review here soon.)
Love of our enemies is a byproduct of a regenerated life.
Pastor cites Jonah as an example of someone who didn't want to preach to his enemies in Nineveh. Yet God was merciful to these people, and Jonah was angry about this. The question God could ask of Jonah would be, "Jonah, why would you deserve mercy and the people of Nineveh would not?"