I read this article just now, and I finally got something to post for the letter O. Tullian is Billy Graham's grandson and reformed. Or at least John Piper let him speak at a conference. So he at least says he's reformed.
I thought this was good because so many people love each other because of what they can get out of each other. There is no altruism, and I can't even fathom God being altruistic although he is. God is the only one who loves people for no reason and without expecting in return.
Here is where Tullian gets lost though. Once God does love you by sending Jesus for your penal substitution, it creates a love in us that will return God's love, something that the unsaved will never know, at least not in a way that matters.
However, this article is still good advice for me as I should love people just because I can. Even if they hate me one week, I still must actively love them. Not with fuzzy feelings in my heart or wishes of good will, but actively seek to do good to them.