Tchavidjian has been accused by some reviewers of creating antitheses between law and gospel and between rest and work. Some have asserted that in Jesus + Nothing = Everything, Tchavidjian denies the work and struggle against sin in the Christian life and some have charged that he is flirting with antinomianism. I would argue, however, that he articulates helpful (even indispensable) distinctions and relationships between these elements of Christianity and that he does not encourage the believer to do away with or devalue either God's law or the struggle against sin.
LAW and GOSPEL
In Jesus + Nothing = Everything, Tchividjian (in the good company of Calvin, Luther, and many others) makes a clear distinction between the imperative and indicative, the law and the gospel. This distinction is often criticized as if the distinction itself creates an antithesis or an opposition, as if there is embedded in this distinction the further claim of LAW = bad/anti-gospel and GOSPEL = good/ anti-law.
However, the relationship between law and gospel, as understood by those who would insist on a clear distinction between the two, would be better stated as LAW = God's good, righteous and holy standard and GOSPEL = God's free gift of Jesus, the perfect fulfillment of the holy standard.
Gospel fulfills law, it doesn't replace it or oppose it. What is important is to understand the relationship between these two good things given by God, and not to either conflate them into one thing or set them in opposition to each other. When law and gospel are not understood as distinct from each other, the result is usually a weakened law--a standard that we think we can fulfill, and also a weakened gospel--Jesus plus something (that we do) equals everything. Tchavidjian goes to great lengths to keep law and gospel distinct in his book.
REST and STRUGGLE
The question then comes down to this: How are we as Christians to understand Christian growth or progress in sanctification? I believe Tchividjian has been wrongly accused by some who claim that he teaches there is no real work (aside from the work of resting in the gospel) in the process of sanctification or in living the Christian life. Again, his distinction has been misunderstood to be an opposition or antithesis.
Tchavidjian argues that as we believe more and more deeply and fully that the Gospel (the perfect, free, fulfillment of God's law given to us in Christ) is true, we then live out of that reality more and more freely. That the gospel itself (our security and standing in Christ) affects change within believers causing us to cling less to our sin, to desire to live obedient lives, and to love God and others more.
He also acknowledges that in life we constantly face temptations to sin and we need a strong foundation, we need stable ground to stand on when we struggle against those temptations. He asserts that our own resolve, or our fear of condemnation, or our methodologies are ultimately insufficient and lacking the real power needed to struggle against sin and to persevere in faith. In fact, only the reality of the gospel--that is, our identity as justified children of God--has the power to motivate us to continue struggling against sin and to endure the inevitable failures we will encounter.
Ultimately, the gospel is the stable ground we on which we stand (and where we can rest) when we fight sin in our lives and also when we (inevitably) see our failure to measure up to God's standard. Without that stable ground, it doesn't matter what weapons we bring to the fight (striving, lists, fear), we will fail and (apart from the gospel) we will lack assurance and peace. We may work hard to prove our right standing with God to ourselves, but we will always be insecure and eventually we will be worn out, worn down by trying to carry the heavy burden of the law on our own shoulders.
However, resting on the unshakable foundation of the gospel, we can fight against sin (and this will involve our own resolve and perhaps methods and other "weapons") and when we fail we will be better able to get up and keep trying.
We can continue to struggle because we have rest.
Though we falter, we will not be defeated because we will know that the victory over sin has already been won and is already ours in Christ. We gain confidence and assurance and perseverance primarily as we believe the truth of the gospel more, not as we achieve more and more success in our struggle against sin.
Tchavidjian describes the relationship (not the antithesis) between resting in the gospel and struggling against sin near the end of his book:
If you're a Christian, then even in the most heated moments of temptation, what you actually desire most deeply is God, not sin, because of the transforming work God has done in you. He's changed you at your core. You're a different person now because of the hard surgical work he's done inside you.
That's why such an important part of fending off temptation--whether it be something Paul lists in verses 5 and 8 of Colossians 3 ("sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry," or "anger, wrath, malice, slander, and obscene talk"), or something else--what's important is simply to first come to terms with who you are, what you've been remade to be. Bring that reality into the moment of temptation, and be reminded by the gospel of who you are now, and of what you want most, even in the face of sin's deception about what you really desire. Identity (who we are) precedes practicality (what we do).
If we would just stop and remember the gospel, we would realize that God really is what we want most, even in our worst moments, no matter how strong the temptation we're battling.
Lasting behavioral change happens as you grow in your understanding of the gospel, and then as you learn to receive and rest in--at your point of deepest need--everything Jesus secured for you. (179)
Notice that in this passage he is describing a relationship between gospel and struggling against sin, not an opposition:
"what's important is simply to first come to terms with [your new identity in Christ]" (italics mine).
"Identity (who we are) precedes practicality (what we do)."
"Behavioral change happens as you grow in your understanding of the gospel" (italics mine).
Tchavidjian is clarifying an emphasis, establishing a priority in our sanctification: It is of foremost importance that we believe the gospel. This priority doesn't preclude effort, struggle, or battling against temptation. But it does establish the foundational necessity of believing in (and resting in) the gospel in order to grow and mature in faith.
Clearly, Tchavidjian sees growth in maturity, and struggling against sin as desirable realities in the Christian life. And clearly he upholds God's law as a good guide for Christian living. The accusation that he advocates a kind of anti-nomianism is unfounded, arising from a misunderstanding of the law/gospel distinction and the relationship between resting in the gospel and following God in obedience.
Michael Horton sums up the relationship between justification and sanctification more clearly and succinctly than I in his discussion of Philipians 2:
Bottom line: The gospel is not the enemy of good works, unless one is seeking justification by obedience, as Paul makes clear in chapter 3. In fact, the gospel is the ground of good works. The goal is both to be clothed with Christ’s alien, perfect, and complete righteousness and to be more and more “filled with the fruit of righteousness that comes through Jesus Christ, to the glory and praise of God” (1:11). So not only when we are resting in Christ for justification, but when we are going out of ourselves to love our neighbors in sanctification, the Triune God has it all under control. We’re only working out that which he has worked for and within us according to his gospel. Holding fast to the word of life, we work out our salvation in the knowledge that “he who began a good work in you will bring it completion at the day of Jesus Christ” (Phil 1:6).The bottom line of my comments here: I encourage those who would seek a fuller understanding of the gospel and of the freedom they have in Christ to read Jesus + Nothing = Everything. You may just find yourself resting in the gospel a little more fully and struggling toward obedience a little more faithfully.