When it comes to religion, humans are wired with law. Since Adam broke the covenant of works in the garden, people have always attempted to please God (or god/gods) by doing something for him. The law that says ‘do this and live’ is part of human DNA. This is why it is so hard for some people to believe a law-free gospel – good news that you don’t have to do a single thing for God to be accepted by him. In fact, you have to stop doing things and receive a gift instead: the Messiah Jesus, who lived, died, and rose again to save sinners.
That humans are law-wired is also a reason why people sometimes sneak the law in the back door of the doctrine of justification. As I’ve heard it said, everyone has a little Pope or Pharisee in his bosom. Paul talked about this in his letter to the Galatian churches, where some false brothers infiltrated the church, sneaking the law in the back door: you have to believe in Jesus and be circumcised to be saved (cf. Acts 15:1). People still do things like this today, mixing a bit of law with the gospel, mixing works with grace. They talk about a “lawful gospel” or say that the gospel includes law, or they say that we are justified by faith alone – but define faith as “faithfulness” or “obedient faith.” These types of statements have been used by advocates of the Federal Vision, which is why historic Reformed/Presbyterian churches have very decisively rejected Federal Vision teaching with a loud and unanimous NO.
In The Gospel Mystery of Sanctification Walter Marshall does an excellent job explaining how the law keeps creeping into the picture of acceptance with God (justification). Sometimes, he says, people want to make conditions to the gospel. Other times, people want to talk about law-obedience in preparation to salvation:
“We are naturally so prone to ground our salvation in our own works, that if we cannot make them procuring conditions and causes of our salvation by Christ, yet we shall endeavor at least to make them necessary preparatives, to fit us for receiving Christ and his salvation by faith” (p. 51-2).
Marshal goes on:
The error [of necessary preparatives] is pernicious to the practice of holiness, and to our whole salvation, in the same manner with that treated of in the foregoing direction [discussion], and may be confuted by the same arguments which are there produced. Whether holiness be made a procuring condition of our salvation through Christ, or only a condition necessary to qualify us for the reception of Christ, we are equally brought under those legal terms of doing first the duties required in the law, that so we may live.
Therefore, we are equally bereaved of the assistance of those means of holiness, mentioned in the foregoing directions, as union and fellowship with Christ, and the enjoyment of all His sanctifying endowments by faith, which should go before the practice of holiness, that they may enable us for it; and we are equally left to labor in vain for holiness, while we are in our accursed natural state, by which our sinful corruption will rather be exasperated than mortified, so that we shall never be duly prepared for the reception of Christ, as long as we live in the world.
Thus, while we endeavor to prepare our way to Christ by holy qualifications, we do rather fill it with stumbling blocks and deep pits, by which our souls are hindered from ever attaining to the salvation by Christ.
Marshall says a lot there! Basically, he notes that whether a person says holiness is part of his acceptance with God or whether a person sees obedience as part of preparation for coming to Christ, both are examples of the law being mixed with the gospel – which actually gets in the way of justification and true holiness! This is exactly what Luther’s first thesis says:
The law of God, the most salutary doctrine of life, cannot advance humans on their way to righteousness, but rather hinders them.
Mixing the law with the gospel in any way, shape, or form, is a deadly concoction. It’s something we need to guard against with all our Christian might. Keep your back doors locked!
The above quotes were taken from Walter Marshall, The Gospel Mystery of Sanctification, “Direction 7.”