Leviticus 19 includes the phrase that Jesus quotes as the second great commandment, “Love your neighbor as yourself.” God gives examples of what this means, anticipating the pharisaical question, “Who is my neighbor?” He includes the poor, the sojourner, the hired worker, the deaf, the blind, the great, the one living near you, and any of the sons of your people. This would pretty much include anyone you might happen to meet or do business with in your daily life.
The whole passage is structured with the refrain, “I am Yahweh.” Why do we love our neighbor? Because Yahweh is who He is and we are His people. In Exodus, Pharaoh refused to let the Hebrews go, saying, “Who is Yahweh? I don’t know Yahweh.” When Moses brought this to God, He responded, I am Yahweh; I have heard the cries of the people of Israel in their slavery and I have remembered the covenant I made with their fathers. I am Yahweh; I will deliver you from your slavery. You will be my people and I will be your God. I will bring you to the land that I swore to give to your fathers. I am Yahweh.
God’s deliverance of His people — the exodus from Egypt — was an answer to the question, “Who is Yahweh?” He does this so Israel would know Him, so Egypt and the surrounding nations would see and know that He is God over all. Likewise, when He says, “You shall be holy, for I Yahweh your God am holy,” or, “Love your neighbor as yourself. I am Yahweh,” it is a reflection of His character, a witness to us and the surrounding world that He is who He says He is. Jesus says, “By this all people will know that you are my disciples, if you have love for one another.”
Paul says it this way, “We are one body in Christ, and individually members one of another.” We love one another because we are one body. “Love your neighbor as yourself.” The gifts we’ve been given, whether it’s service or teaching or generosity or any other thing, are given for the benefit of the whole body. The hand has the gift of grasping and the eye the gift of seeing, but these only make sense in the context of the body. The eye doesn’t see just for the sake of the eye, but for the rest of the body. So we love one another because we are members of one another. We love one another so that the world will see and know that Jesus is Lord over all.