“Blessed is the one… whose delight is in the law of the Lord, and who meditates on his law day and night.” (Psalm 1:1a,2)
Discussions about the Old Testament Law can be difficult. We tend to fear either legalism or antinomianism, which can often then drive us to the other. Legalism effectively denies the gospel, promoting works-righteousness and turning the law (or usually a distortion of the law) into how we attain a right standing with God. Antinomianism (anti-nomos, literally anti-law) is the opposite, arguing that the law, in particular the Old Testament law, has no relevance at all.
All Christians should affirm that we are saved by faith, but that faith is never alone. We often misunderstand the New Testament to be abolishing the law, but the key is that we are no longer under the law. It is not a burden that we need to fulfil to be loved by God, rather it is a standard for obedience by which we, very fallibly, show our love for God: “if you love me, you will keep my commandments.” (John 14:15)
Jesus says “‘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 neighbour as yourself.’” (Matthew 22:37-39) The question we are left with is: what does it mean, or what does it look like, to love God and neighbour? We like to define for ourselves what ‘love’ means. We hear ‘love is love’ as though the meaning of love is simply self-evident and obvious. But is it? Well Jesus tells us immediately after: “All the law and the Prophets hang on these two commandments.” (v40) In the sermon on the mount, “Jesus challenges wrong uses of Torah and asserts there is a right way of understanding it, under His direction… Jesus’ hearers are to listen to Him because He will provide them with the right way of interpreting Torah and of building upon it.” Jesus has not abrogated it, he has fulfilled it and, in fact, reinforces it (Matthew 5:17-19).
But what is it for? Burnside argues “Biblical law [is] an integration of different instructional genres of the Bible which together express a vision of society ultimately answerable to God.” Joe Boot commenting on Romans 3:19-20 writes “[Paul] makes plain that knowledge of sin comes by the law and that the whole world stands accountable to God in terms of it. The salient question regarding the relevance of biblical law today is whether or not we still believe the societies of men in the earth remain accountable to God. The Christian must answer an emphatic ‘Yes.’”Instinctively, the majority of Christians know this. We are often happy to speak out against an injustice which is fairly uncontroversial (though not necessarily less serious), for example, human trafficking, but when it comes to issues that maybe Christians and the world disagree on, say abortion or gay marriage, we can slide into thinking we are “imposing our Christian morality.” The difficulty we have though is there is no neutrality, each law has a value attached to it and so where do we get our values and morality from?
History is helpful here. The interpretation and application of biblical law is not anomalous in history: “The ninth-century law-code of King Alfred the Great… was the first and only codification of Old English law and was based, explicitly, on the laws of Moses (specifically, a lengthy extract from the Covenant Code of Exodus).” John Owen “used and interpreted the Old Testament… [to deduce] the duties of the Christian magistrate (i.e. the English Parliament) directly from the duties laid down in the Old Testament for the king of Israel.” Our Queen at her coronation was asked “Will you to the utmost of your power maintain the Laws of God and the true profession of the Gospel?”
It is a modern phenomenon in the church for us to flinch at some parts of the Old Testament and our language can stray awfully close to denying the goodness of God in the Old Testament. Yet we know that God is good and unchanging. Applying the law is difficult, but importantly Biblical law is presented not as rules but as wisdom. There will be disagreement about how we apply it, but today we are not even asking the question let alone looking for an answer.
We often restrict our Christian living to the church and evangelism, and not the Lordship of Christ over all of life, including society. Paul writes “there is no authority except that which God has established… For the one in authority is God’s servant for your good... They are God’s servants…” (Romans 13:1b,4). Clearly here, the state, as God’s servant, is subject to God, and is therefore to submit all its authority under God. Calvin writes “when David says, “Be wise now therefore, O ye kings: be instructed, ye judges of the earth;” “Kiss the Son, lest he be angry” (Psalm 2:10, 12), he does not order them to lay aside their authority and return to private life, but to make the power with which they are invested subject to Christ, that he may rule over all.” There is a misunderstanding today in the church for us to think that separation of church and state means separation of God and society, but that is impossible.
Evangelism and cultural engagement go hand in hand. Lives need to be transformed by the love of God to understand the law of God, otherwise we are preaching works righteousness. But at the same time, as Christians, we need to pursue justice and derive our understanding of justice from the Bible. Jesus’s ministry began with “Repent, for the kingdom of heaven is at hand.” (Matthew 4:17) This gospel includes the transformation and reconciliation of all things under his Lordship (Colossians 1:15-20, Ephesians 1:4-10), but this cannot be entered into without repentance through Christ’s substitutionary death on the cross taking the penalty that was due us, triumphing over death and evil. We need both.
We need to have a positive social vision for society, contending and engaging positively for justice, not autonomously based on our feelings or the world’s agenda. And through proclaiming Christ and working to discern what this application looks like, we will actually attract people to Christ (Matthew 5:16, Deuteronomy 4:6).
Perhaps if we took Deuteronomy 22:8 more seriously as a society, building a parapet to protect people from falling off, we might have better building standards and Grenfell might have been avoided? Or Deuteronomy 24:15 “you shall give him his wages on the same day” might challenge the common practice of supermarkets paying farmers months later. We might flinch at the first part of Deuteronomy 25:3 “the judge must not impose more than forty lashes”, but this is in the context of ensuring guilty offenders are “not degraded in your eyes” – a challenge for us in how we treat prisoners, ensuring we affirm their dignity and value despite their crimes. But it will also bring us into conflict with the world. It may not be popular to say it, but the sexual permissiveness of society is causing untold damage to individuals, families and the country more broadly. We should feel no shame about upholding marriage as a positive good for society that brings freedom and security.
People still need to turn to Christ and social transformation cannot happen without evangelism and people coming to know the grace of God, but it is about being a people that loves God and loves neighbour, that is what it means to be salt and light (Matthew 5:13-16) and to be holy (1 Peter 1:13-16). Living in the culture we are in, we must “seek the welfare of the city where I have sent you into exile, and pray to the Lord on its behalf, for in its welfare you will find your welfare” (Jeremiah 29:7). Let us begin then by joining with the Psalmist in declaring “Oh, how I love your law!” (Psalm 119:97).
 Jonathan Burnside, God Justice and Society, pxxxii
 Joe Boot, Mission of God, p257
 Peter Toon, God’s Statesman: The Life and Work of John Owen (Exeter: The Paternoster Press, 1971), p. 177.
 Burnside writes "The study of biblical law enables us to pursue justice. Its application emerges not only from “rules” but from narrative and worldview. It also means internalising a fixed text and improvising a faithful response that is shaped and constrained at every point by practical wisdom." Jonathan Burnside (2017) Words of Wisdom, Words of Prophecy: Why and How Biblical Law Speaks in the Public Square, Political Theology, 18:7, 560-576,
 Joe Boot has written a helpful exposition of Romans 13:1-5 here https://christianconcern.com/resource/the-limits-of-civil-obedience-the-meaning-of-romans-13/
 Institutes, IV.xx.5