Few biblical texts carry the weight, simplicity and the reach of what Jesus called the ‘Greatest Commandment’ found in Deuteronomy 6:4-5. It stands at the heart of Israel’s faith and, crucially, at the heart of Jesus’ teaching and all the teaching later expressed by the Apostles.
“Hear, O Israel: The LORD our God, the LORD is one. You shall love the LORD your God with all your heart and with all your soul and with all your might.” (Deut 6:4-5, ESV)
The ‘Greatest Commandment’ is not merely a confession. It is a summons. The opening word, “Hear” (Hebrew shemaʿ), means more than listening. In Scripture, to hear is to obey. Hearing and doing belong together. Israel is called to respond with a whole life shaped by love for the one true God.
That claim of oneness is not abstract theology. “The LORD is one” speaks of exclusivity and loyalty. Israel belongs to one God (so do we) and that one God will tolerate no rivals. The “love” spoken of here (Hebrew ‘āhaḇ) is covenantal. It is not primarily about feeling, but about allegiance expressed in obedience.
The piling up of phrases – heart, soul and might – leaves no room for half-measures. The heart is the centre of thought and will. The soul is life itself. Might includes strength, resources and capacity. The Greatest Commandment presses one truth home: nothing is untouched by our love for God.
Even within Deuteronomy there is a realism. Moses knows the problem is not the clarity of the command but the condition of the human heart. Later, in Deuteronomy 30, he speaks words that hint at something much deeper:
“And the LORD your God will circumcise your heart… so that you will love the LORD your God with all your heart and with all your soul, that you may live.” (Deut 30:6)
Here the burden shifts. Loving God fully is not presented as an achievement. The heart itself must be changed by God. The Old Testament recognises the gap between God’s law and human ability. Wholehearted love requires divine action.
This anticipation prepares the way for Jesus. When asked about the greatest commandment, He does not innovate. He quotes Deuteronomy 6:4-5 directly (Mark 12:29-30). For Jesus, this is not one command among many. It is the centre of the whole Law.
The Sermon on the Mount does not replace the ‘Greatest Commandment.’ It unfolds it. In Matthew 5-7, obedience is driven inward. Murder is traced back to anger. Adultery to lust. Truthfulness to the heart, not oaths. Jesus’ repeated “But I say to you” intensifies the law rather than abolishing it. God’s claim reaches the inner life, exactly as the ‘Greatest Commandment’ demands.
The parables do the same work, but through story rather than sermon. They expose divided hearts and call for undivided love.
The Parable of the Sower opens with a familiar challenge: “He who has ears, let him hear.” Some hear and resist. Others respond briefly, but without depth. Still others are choked by rival loves: wealth, worry, distraction. Only the good soil hears and bears fruit. The issue is not exposure to the word, but whether God is loved without competition.
The Parables of the Hidden Treasure and the Pearl press the same point. In both, the discovery of the kingdom leads to joyful, costly action: “He goes and sells all that he has.” This is not legalism. It is a reordered desire. The kingdom becomes the supreme good. God is loved with all one’s might.
Other parables sharpen the edge. The Two Sons show that profession without obedience is hollow. The Good Samaritan emerges directly from a discussion of the ‘Greatest Commandment,‘ showing that love for God cannot be separated from love for neighbour. The Rich Fool exposes a life looking inwards, full of possessions but empty of God.
All of this finds its clearest expression in Jesus’ words: “No one can serve two masters.” One God. One allegiance. One love.
The ‘Greatest Commandment,’ then, is not merely background to Jesus’ teaching. It is its backbone. In Christ, it becomes more than a command to obey. It becomes a life to enter, a kingdom shaped by undivided devotion to the one Lord who first works in our hearts, enabling us to love Him fully.