God has called us to be relational by loving him and one another. The cross illustrates this by showing that we relate with God vertically and with people horizontally. If you do not relate with people life becomes a drudge, difficult and horrible.
People are the ones that bring joy to us; we laugh with and share our dreams with them. The Bible says, "Beloved, let us love one another, for love is of God, and everyone who loves is born of God and knows God" (1st John 4:7-8).