Jesus gave the two greatest commandments for all humanity in Matt 22:37-40. The first is that we are to love God. We can only love God because he first loved us, and we are called to love him according to how he has loved us. Love is not just a feeling or an action. Love is a constant longing for, a desire for, and a choosing to promote someone else higher than yourself. We are called to love God with every part of our life in every possible way. The church must promote love for God above everything else or we will fall into the sin of loving ourselves. Jesus’ second command follows from the first.
We are called to love the brothers and sisters in the same way Christ loved the church. He considered her interests above his own by dying for her and he counting her as more important then his own well being (Phil 2). He laid down his life for her, confronted her with her sin, and comforts her with healing. Christians are called to love one another sacrificially in this way. We love one another for the purpose of experiencing Christ in one another, perfecting the love of God in us, glorifying Christ, and giving evidence to the world that God is love (they will know us by our love).