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Why do people follow God’s law, both then and now? We do it because we love God, and we want to serve Him with our lives. It has always been that way, and it will always be that way. Jesus addressed this issue directly (Mk 12:28-34), so let’s look at what He had to say.
And one of the scribes came up and heard them disputing with one another, and seeing that he answered them well, asked him, “Which commandment is the first of all?” (Mk 12:28)
This goes to show you that stereotypes aren’t always accurate; a scribe is the one who asks this question. The context which prompted the question is Jesus’ dispute with the Sadducees about the validity of the resurrection (Mk 12:18-27). This man is a Pharisee. He’s somebody who is very concerned with the letter of the law. So, naturally, he wants to know what the greatest commandment is – so he can follow it!
Jesus answered, “The first is, ‘Hear, O Israel: The Lord our God, the Lord is one; and you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength.’ The second is this, ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these,” (Mk 12:29-31).
Here is the content of Jesus’ answer, from Deuteronomy 6:4-5. Think about what it tells us about why God’s people should obey His law.
Our God is the Lord
God is your master. He is in complete charge of your life, your soul, your blessings, your cursings, your destiny. If you’re a Christian, God created you as a new person in Christ “for good works, which God prepared beforehand, that we should walk in them,” (Eph 2:10). You were saved in order to serve the Lord, and work for Him.
God is your Lord! If He saved you, then you are now a willing and enthusiastic slave for righteousness. This is the foundation for Jesus’ answer.
The Lord is One
There is only One legitimate Lord you can serve – everything else is a pagan counterfeit. He is the God of the Hebrew Bible and the Christian Scriptures. He is the God of the First Covenant and the God of the New Covenant
You will love God with all your heart, soul, mind, and strength
You must love God with everything you have, with every fiber of your being! These terms are not synonymous (we could look at each of them individually), but together they express a simple concept – a complete, all-encompassing love for God! Anything done for a reason other than this is counterfeit, and God is not pleased by it. This is why God’s people should want to do what He says.
You will love your neighbor just as you love yourself
Who is your neighbor? In the context of Leviticus 19:18 (which Jesus quoted from), your neighbor is a covenant brother and sister – including a believing Gentile (cf. Lev 19:34). In short, Jesus is talking about “brotherly love,” (cf. 1 Jn 4:20). You should love and value your Christian brothers and sisters just as much as you love and value yourself.
All of the Old Covenant law can be summed up in these two commands (cf. Mt 22:40). God is your Lord, therefore you exist to serve Him. Your Lord is One, therefore any other worship is idolatry. So, you must love God with everything you have. This is the only appropriate motivation for service.
- You serve God because He saved you from yourself, knowing who you are, what you have done, what you are doing now, and what you will do in the future.
- Because you’re so grateful and love Him so much, you’ll want to serve Him with your life.
- And because all this is true, you also love your covenant brothers and sisters because, together, you’re each part of God’s family.
Jesus refers to these two commandments as one singular commandment because, together, they sum up the entire teaching purpose of the law. They’re inseparable. If you love God, then you’ll love God’s children, because they’re your brothers and sisters.
And the scribe said to him, “You are right, Teacher; you have truly said that he is one, and there is no other but he; and to love him with all the heart, and with all the understanding, and with all the strength, and to love one’s neighbor as oneself, is much more than all whole burnt offerings and sacrifices” (Mk 12:32-33)
Why does the scribe have such insight? Isn’t he supposed to be a legalistic hypocrite!? This is why we must always remember we can’t read the Bible like it’s cardboard. This is the story of real people, with real minds of their own, who act like real people would actually act. It’s always dangerous to over-generalize about people; it’s true today and it was true then.
Most of the scribes were legalists like the Pharisees, but not all of them were! This scribe seems to be genuinely sincere. It is likely God was drawing this man to saving faith. I like to think he repented and believed one day. After all, some of the Pharisees did believe (e.g. Nicodemus, Acts 15:5).
And when Jesus saw that he answered wisely, he said to him, “You are not far from the kingdom of God.” And after that no one dared to ask him any question (Mk 12:34; cf. Mt 22:34-40)
This is Jesus’ inspired statement about why God’s people should obey God’s law; especially the Old Covenant law. You obey God’s law because you love Him, and want to serve Him. Real salvation produces real fruit. That fruit is wholehearted love for God, which proves itself by action.
The entire bible agrees.
 William L. Lane suggests the man could be a Sadducee, because that group had its own group of legal interpreters (The Gospel of Mark, in NICNT [Grand Rapids, MI: Eerdmans, 1974], 431). I doubt this. I’m not aware of any place in the NT where the phrase γραμματεύς refers to the Sadducees; however, the reference to “scribes of the Pharisees” (Mk 2:16) is intriguing, suggesting different sects may have had their own scribes.
Generally, however, the scribes are associated with the Pharisee party. Add to it that Jesus had just handily dispatched the Sadducees’ ridiculous argument against the resurrection. If this particular scribe were a Sadducee, one would not expect him to engage in a discussion over which commandment was first of all! This is a Pharisaical question, through and through. A Sadducee would likely be smarting over the discussion which had just ended. “Most scribes aligned with the Pharisees in their theology, including their teaching on the resurrection and the authority of Scripture,” (Mark L. Strauss, Mark, in ZECNT [Grand Rapids, MI: Zondervan, 2014], 541).
 There is more to this question, but I don’t have time to go into it here. See Lane (Mark, 431-432) and James R. Edwards, The Gospel According to Mark, in PNTC (Grand Rapids, MI: Eerdmans, 2002), 370-371.
Lane observed, “Both the question and its presuppositions stem from a piety of human achievement, supported by scribal interpretation of the biblical mandates (Lane, Mark, 431).
 The UBS-5, TR and BYZ are each identical to the LXX (Rahlfs) here. Very interesting! This phrase can be rendered in a variety of ways, depending on how you interpret the nominatives – just look at the different English translations. I rendered it, “Jesus answered that [the] most important is, ‘Listen, Israel! Our God is Lord. [The] Lord is one.”
 “Jesus demands a decision and readiness for God, and for God alone, in an unconditional manner. Clearly this cannot be the subject of legal enactment. It is a matter of the will and action. The love which determines the whole disposition of one’s life and places one’s whole personality in the service of God reflects a commitment to God which springs from divine sonship,” (Lane, Mark, 432-433).
 See Craig A. Evans, Mark 8:27 – 16:20, in WBC, vol. 34b (Nashville, TN: Thomas Nelson, 2001), 264.
 The Greek is clear here: μείζων τούτων ἄλλη ἐντολὴ οὐκ ἔστιν (“there is not another command greater than these”). Strauss, however, disputes this point grammatically (Mark, 546 [fn. 11]).
 Evans suggests they sum up the Decalogue (Mark 8:27 – 16:20, 265). I don’t have time to elaborate that here.
 Walter W. Wessel, Mark, in EBC, vol. 8 (Grand Rapids, MI: Zondervan, 1984), 736.