Let's face it: Luke is a hippie. "All you need is love." "Make love, not war." Doesn't sound too different from Luke, right?
There are at least three types of love worth tracking throughout Luke's story: love among people, God's love for mortals, and people's love for various non-human things, like honors, wealth, or God. The common thread here is the Greek word agape, which we see at least twelve times in Luke's gospel. It might be Greek to you, but that doesn't let you off the hook. Track it through the English and see how Luke interprets the oh-so-abstract concept.