What is the greatest commandment?

The Sadducees are followed by a representative of the scribes, who were the interpreters of the law, and believed that some laws were of greater importance than others. He asks the Lord to give His judgment as to "Which is the first commandment of all?" In His perfect wisdom the Lord passes over the ten commandments which would naturally occur to the mind of man, and selects certain great exhortations from the Pentateuch which sum up the law and express man's whole duty to God and man.

Moses sums up in two brief sentences what the law implies in its first table. First, the unity and immutability of God: "Hear, O Israel: The LORD our God, the LORD is one" — and founded on this, His claim to the undivided allegiance of man: "You shall love the LORD your God with all your heart and with all your soul and with all your might." If there is only one God, there is none beside Him to divide the heart with, and He claims the whole of it in the most absolute way. The words stand for the inner man, with all his affections, and in their full energy.

The very fact that the law's demand was love shows that it was God's own nature which desired this; and that nature is love — "God is love." Nor does the law simply demand love from the whole heart, as is sometimes said, but rather from the whole being.

Here lies the secret of all true practical religion. Without this all is worthless to God. "My son, give me your heart." Where the heart is given, all will be right. The heart may be compared to the regulator of a watch, which acts on the hair-spring, and the hair-spring acts on the main-spring, and the main-spring acts on the hands as they move round the dial. If your watch goes wrong, it will not do merely to alter the hands; you must touch the regulator.

The first responsibility of man is to maintain the unity of the Godhead according to the Scripture which says, "Hear, O Israel: The LORD our God, the LORD is one." It follows then that man is responsible to love God more than himself, and to the exclusion of every other object as a competitor; and secondly, to love his neighbour as himself. This is the summing up of the whole law and presents the whole duty of man upon earth according to the law. If these two laws were kept, none of the other laws would be broken.

Such is the law. Its demands are strict, its measure perfect, its standard unalterable, inflicting death on the transgressor, without any promise of mercy... Who, then, can lay claim to life on the ground of the law? Who can say, I am clean, I am pure, I have never broken your commands at any time? Blessed be God, there was One who could say, "I have glorified you on earth, having accomplished the work that you gave me to do." He loved the Lord His God with all His heart, and with all His soul, and with all His mind, and with all His strength; and He proved that He loved His neighbour as Himself by redeeming him with His own precious blood.

They had not yet known the great display of God's love in the gift of His Son, as we have known it. We can indeed say, "We love because he first loved us" (1 John 4:19), and we know the love displayed in surpassing degree. Still, God had shown His love towards them as a people... They should have loved Him in return.