Matthew records Pharisees testing Jesus with a question, "Teacher, which is the greatest commandment in the Law?" (Matthew 22:36). Jesus replied, " 'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment. And the second is like it: 'Love your neighbor as yourself.' All the Law and the Prophets hang on these two commandments" (Matthew 22:37-40 NIV).
In their obedience, the Pharisees had lost sight of the very heart of the matter - loving God. External observance of the commandments without love is simply an empty form. Jesus warns elsewhere, "Woe to you, teachers of the law and Pharisees, you hypocrites! You clean the outside of the cup and dish, but inside they are full of greed and self-indulgence. Blind Pharisee! First clean the inside of the cup and dish, and then the outside also will be clean" (Matthew 23:25-26 NIV).
To loving God means to receive cleansing from the inside first. Without that cleansing, our obedience cannot be genuine. Even when we appear to be righteous, our obedience is corrupted by bad motives.
God gave us this central commandment to love God in Deuteronomy 6:1-25. So this was not new when Jesus spoke it to the Pharisees. It has always been the spirit in which we must keep all the other commandments. Without following this one command, we are not really keeping any of the others.
Failing to be in communion with God personally and to love him fervently leads to misinterpretation of the Bible. Jesus said: "You are wrong, because you know neither the Scriptures nor the power of God" (Matthew 22:29 RSV; see also Matthew 15:3).
Jesus said to "Love the Lord your God with all your heart and with all your soul and with all your mind" (Matthew 22:37 NIV). So this is the first and greatest - but not the only. Jesus also said, "If you love me, you will keep my commandments" (John 14:15 RSV). That is, if we truly love God, we will keep all the other commandments as well as this greatest one. We cannot rightly follow the others without first loving God but from rightly loving God flows obedience to the others.
Some today understand love as merely a happy feeling of friendliness or good will. They wrongly think that If they feel good about the idea of God or have internal peace that knowing and obeying his commands are not essential. Situation ethics has claimed that love replaced all the commandments. But that is not the Biblical view of loving God. Love does not replace Commandments. Love gives us the right motive so that we genuinely can obey the Commandments.
True love drives true behavior. "Let us not love with words or tongue, but with actions and in truth" (1 John 3:18 NIV).
True love of God means honoring Him, revering Him, and paying close attention to His desires as expressed in the Bible. "Do not merely listen to the word, and so deceive yourselves. Do what it says" (James 1:22 NIV).
With a proper understanding of what Jesus said we avoid legalism on one side and an irresponsible idea of freedom by indicating that God does really expect us to obey him on the other. God wants us to please Him by following the ways He has revealed.
Jesus continues with, "The second is like it: 'Love your neighbor as yourself'" (Matthew 22:39 NIV). More explicitly, "We love because he first loved us. If anyone says, "I love God," yet hates his brother, he is a liar. For anyone who does not love his brother, whom he has seen, cannot love God, whom he has not seen. And he has given us this command: Whoever loves God must also love his brother" (1 John 4:19-21 NIV). Loving God empowers us to love other people. The focus on love helps us not to settle for a minimum concern for neighbors, but to reach out to them. Love helps us to understand the real thrust of the commandments, and to give us concern for actual obeying, not merely listening (James 1:22).
And all of this is impossible outside of God's saving grace and Christ's substitutionary work on the cross. "In this is love, not that we loved God, but that He loved us and sent his Son to be the propitiation for our sins" (1 John 4:10 NASB). Jesus loved us perfectly and gave himself for us (Galatians 2:20). He saved us when none of us could save ourselves (Romans 5:6-10). And now, when we put our trust in him, we are united to him, and we are transformed so that we can imitate the pattern of his love: "A new commandment I give to you, that you love one another, even as I have loved you, that you also love one another. By this all people will know that you are my disciples, if you have love for one another" (John 13:34-35 RSV). Through Jesus Christ we receive not only understanding of God's will, but power and motivation to serve Him. In receiving His love, we can, in turn, love others.
We must have His life to avoid the common traps of conservative legalism and liberal situation ethics (or the avoidance of any truth under the banner of false love).