According to Jesus in Matthew 22:39, Mark 12:31, and Luke 10:27, the second greatest commandment is: “Love your neighbor as yourself.” While it does not appear in Deuteronomy 6 with the greatest commandment, it is part of the Law set forth in Leviticus 19:18 (NIV).
“Neighbor” is a familiar term in the Old Testament. In fact, it appears in the ten commandments: “You shall not give false testimony against your neighbor.” (Exodus 20:16) When neighbor is used in the Old Testament, it always seems to mean someone nearby — a fellow Israelite.
In addition to the gospel passages of scripture where Jesus combines the first and second greatest commandments, the New Testament has additional versions of “love your neighbor.” (Matthew 19:19; Romans 13:9) In James 2:8, an exclamation point is given to the importance of this commandment: “If you really keep the royal law found in Scripture, ‘Love your neighbor as yourself,’ you are doing right.”
Another principle that’s closely linked with the second greatest commandment is found in Matthew 7:12: “So in everything, do to others what you would have them do to you.” (See also Luke 6:31.) Here Jesus adds: “[F]or this sums up the Law and the Prophets.” No reference to the greatest commandment — only something akin to the second greatest stands for the “Law and the Prophets.” There can be no doubt that, according to scripture itself, one of its most important principles is the way we treat other people.
But love of neighbor can’t exist without love of God — can it? In I John 4:19-21: “…Whoever claims to love God yet…does not love their brother and sister…cannot love God..Anyone who loves God must also love their brother and sister [sometimes translated “others” or “one another].”
Any discussion of the second greatest commandment is incomplete without examining Luke’s expansion of the meaning of “neighbor.” We’ll do that tomorrow.