The New Testament writers adopted agape as the standard word for love. We think this means that agape must also have some softer meanings besides sacrifice, death on a cross, giving away our possessions, and giving our body to be burned. But agape didn't make the Cross; the Cross made agape. The Cross isn't a subset of agape; agape is a subset of the Cross. The fact that the writers chose agape as the primary, defining word for love in the New Testament, and thus for life in the Christian community, shows how radically the New Testament redefines love from the perspective of the Cross.
It also shows how radically the New Testament defines our concepts of friendship. For Jesus tells his disciples: "This is my commandment, that you love [agape] one another as I have loved you. No one has greater love than this, to lay down one's life for one's friends [philos] (John 15:12?13).
If we have agape for the people we serve, then being loyal to them, having compassion for them, and liking them are a cinch. Jesus mustered the latter three loves without difficulty, but when faced with showing agape, he sweat blood.