Jesus said that it is not what goes into a person that makes them unclean, but what comes out of their heart. Out of the abundance of the heart come all kinds of sin: evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander. This failure of heart, what Christian theologians have described as concupiscence or our tendency to sin, is described by the Apostle Paul in a tight little passage as the consequence of false worship.
Despite the beauty and delight of the world around us, we refused to respond to our Creator with a due sense of thankful or praise (Romans 1:21). Instead, we turned to from the Creator to the creation, worshipping it in his place, desiring the things he had made rather than our maker (Romans 1:23, 25). Through idolatry, our hearts became just as darkened and our thinking futile as the things we worshipped.
Paul is probably picking up on the idea prevalent in the Old Testament that we become what we worship. This is seen in Isaiah; the prophet is commissioned to preach to his idolatrous generation with the result that they deaf, blind, and dull hearted (Isaiah 6:9-10) – just like the idols they worship (Isaiah 42:8, 17-25)! Hence why one of things the Servant of the Lord brings is the restoration of sight to the blind.
Likewise, the Apostle John can describe our hearts in this manner. John can urge his readers to guard against idolatry (1 John 5:21; cf. 1 Corinthians 10:7, 14) because he knows that our concupiscence lies in our love of things in God’s good world (1 John 2:15-17). The problem lies not out there; it lies in mangled love or over-desires: ‘the desires of the flesh, the desires of the eyes, pride in possessions’. It is not hard to imagine as Andrew Cameron does that this is John’s commentary on that moment in the garden when sin was let loose on the world: (cf. Genesis 3:6) good for food’ [desire of flesh]; ‘pleasing to the eye’ [desire of eyes]; ‘desirable for wisdom’ [pride]. What John describes is our thankless, obsessive, destructive misappropriation of the Creator’s creation. Our love for the wrong things has bent us out of shape.
It was his reflection on these verses that led St Augustine to describe our propensity to sin as disordered love. Human beings are liturgical creatures – we are made to worship something. In our refusal to thank and glorify God, our hearts have turned to find something else to worship.
These are thy gifts; they are good, for thou in thy goodness has made them. Nothing in them is from us, save for sin when, neglectful of order, we fix our love on the creature, instead of on thee, the Creator. (City of God, XV.22)
What is needed is for our misdirected hearts to be reordered, for our hearts remain restless until they come to rest in that for which they were made.
But living a just and holy life requires one to be capable of an objective and impartial evaluation of things: to love things, that is to say, in the right order, so that you do not love what is not to be loved, or fail to love what is to be loved, or have a greater love for what should be loved less, or an equal love for things that should be loved less or more, or a lesser or greater love for things that should be loved equally. (On Christian Doctrine, I.27-28)
Millennia later, the former Augustinian monk Martin Luther diagnosed the human condition in a similar way. According the Luther, our life and worship is incurvatus in se, turned in on ourselves.
Our nature, by the corruption of the first sin, so deeply curved in on itself that it not only bends the best gifts of God towards itself and enjoys them (as is plain in the works-righteous and hypocrites), or rather even uses God himself in order to attain these gifts, but it also fails to realize that it so wickedly, curvedly, and viciously seeks all things, even God, for its own sake. (Lectures on Romans)
In like manner, John Calvin wrote in his Christian Institutes that “the human heart is an idol factory” (Institutes of the Christian Religion, I 11.8). Our hearts and minds are perpetually industrious in imagining new things to love and worship. This long tradition of equating sin with idolatry was neatly summarised a few years ago by moral theologian Oliver O’Donovan:
[I]t is possible, notwithstanding the truth that we love and know only the good, also in a sense to love evil. We love evil by resting in the pattern of loves and dreads that comes immediately to us, treating our dreads as though they were equally real with the goods we love. ... This is perfectly expressed in the traditional Christian doctrine of original sin, described memorably by Martin Luther as an incurvatus in se, a self-enclosure. In sin we divide the good world God has made into two “worlds”, one good and the other evil, and we make our own contingent perspectives the criterion for the division. And this gives a new, negative sense to the term “world”, which we have hitherto spoken of positively as God’s creation. This negative sense is characteristic of the New Testament, and points to the reality a constructed world, a world of our own imagination, pitched over against the created world and in opposition to it.
The great human tragedy is that despite being the divinely commissioned image-bearers in the world, we turned from reflecting that image to the creation and love of other images. We exchanged the truth of God for a lie, and worshipped idols of our fashioning. Out of the abundance of the heart comes all kind of impurities, and our hearts had grown ruinous. Yet whilst the human heart spewed forth impurity, the Jesus Christ – the very image of God (2 Corinthians 4:4; Colossians 1:15) – came forth to heal our hearts. His work is summarised by Hebrews 1:3 as such:
He is the reflection of God’s glory and the exact imprint of God’s very being, and he sustains all things by his powerful word. When he had made purification for sins, he sat down at the right hand of the Majesty on high…
Hebrews goes on to say that this purification came through Jesus’ own blood (9:14). He has put away sin once and for all (9:26), enabling those purified by him to serve the living God. The end result as pictured in Hebrews 13 is a life issuing forth as a sacrifice of praise. Those purified by Jesus the great high priest are enabled to live a life of worship to God. Along the same lines Paul encourages the mind set on the Spirit to be transformed, as the body worships God (Romans 12:1):
I appeal to you therefore, brothers and sisters, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship.
This is the antithesis of the perverted worship of Romans 1. Whereas in Romans 1 humans were dishonoured in their bodies, worshipping and serving creatures, disapproving of God which issued in a depraved mind, in Romans 12 Christians are instructed to present their bodies in the service and worship of God, which leads to the renewing of their minds, that they may approve God’s will. The achievement of Christ is to turn God’s enemies into those who are by the Spirit conformed to the image of God’s Son. We are set free from sin to respond to God by grace. In other words, we are turned from sinners into singers. We do not live under slavery to sin. The prayer of conversion is, with John Donne, that God would “Come | And recreate me now grown ruinous.” We are made fit to worship the true and living God. Far from being hostile towards and unable to please God, I am someone who lives for the praise of God’s glory. Rather than being incurvatus in se, I live (in another of Luther’s phrases) coram Deo; that is, before God, before his face, and in his presence.
This is not to deny the presence of sin in Christians, what Don Carson describes as “shocking, inexcusable, forbidden, appalling, out of line with what we are as Christians.” But to be a Christian is to have one’s darkened heart renewed by the Spirit, so that the abundance of this heart, by God’s grace, produces fruit. Having been purified by our high priest, we are transformed from idol makers to glory reflectors, from incurvatus in se to coram Deo, from sinners to singers.
We know that our old self was crucified with him so that the body of sin might be destroyed, and we might no longer be enslaved to sin. (Romans 6:6)
Through him, then, let us continually offer a sacrifice of praise to God, that is, the fruit of lips that confess his name. (Hebrews 13:15)
 Andrew Cameron, Joined-up life: A Christian account of how ethics works (Nottingham: IVP, 2011), 52-53.
 Oliver O’Donovan, New College Lectures 2007: Lecture 2 ‘Admiring’. http://www.newcollege.unsw.edu.au/newcollegelectures.html.