I like the penetrating analysis of idolatry and gospel by McCaskill in various places especially in regard to union with Christ. He writes that “our flesh will continue to manifest itself in idolatry whenever it is not seen for what it is and treated with its antidote, the personal presence of Jesus Christ acting through his Spirit.” 
Recognize Idolatry as the Prime Enemy of our Life
He like Waters, seems to merge the Spirit of Christ and the Holy Spirit as one in economic term in any case. I would certainly say that the spirit of Christ is different from the Holy Spirit for sure. However, I agree in economic terms, they function in one accord, a seeming mergence at the resurrection of Christ and thereafter the imputation of the Spirit to us. In any case, Macaskill goes beyond the normal teaching of idolatry like what I heard from Tim Keller saying that anything that is of or above God in our lives’ passion, longing, love, is really idols. That’s why Duncan has taught correctly that atheism is not the biggest problem in the world, in fact, they only form a slither of world population, but what’s really bothering Christianity and God is idolatry. 
And since idolatry occupies such a central sleek dangerous dark spot in our lives, what we learn from Keller and a whole lot of reformed theologians and absolutely vital, what Macaskill brings it to another level.
Holy Spirit or Spirit of Christ
He is saying that the antidote for idols is the presence of Jesus Christ. Usually in the post resurrection of Christ, we would call it as the presence of the Holy Spirit. Indeed the Spirit empowered life is all over the bible, and the Spirit convicts of sins:
John 16:7–11 “ 7 Nevertheless, I tell you the truth: it is to your advantage that I go away, for if I do not go away, the Helper will not come to you…..8 And when he comes, he will convict the world concerning sin and righteousness and judgment: 9 concerning sin, because they do not believe in me; 10 concerning righteousness, because I go to the Father, and you will see me no longer; 11 concerning judgment, because the ruler of this world is judged.” (italics mine)
Jesus himself talked about sending the Holy Spirit as our Helper in doing three things: convict us of sins, righteousness ,and finally judgement. So I and a whole lot of pastors will teach it’s the presence of the Holy Spirit.
Any effort apart from Christ is Idolatry
He is right to say that if we begin to think or speak about any part of Christian life and ethics apart from Christ, our flesh will turn into idolatry. That’s what is called moralism or religion, not faith in Christ kind of Christianity , which is Christ centered, not law centered. He goes even further today that even the commandments of God, taken in isolation from Jesus, will become the stuff of idolatry because the commandments are easier to deal with than God himself. Just to obey a set of laws or commandments in order to overcome sins or become ethical, has immediately degraded true Christianity from faith in Christ to a religion that kills. It’s like 2 Cor 3:6 days the letter kills, but the Spirit gives life. Definitely, by not abiding in Christ as a personal savior of ours, we will degrade really fast into idolatry. As Jesus said, “I am the vine…”. So its sharp to say that even the Ten Commandments can become our idol if we don’t embrace the presence of Christ.
From Status to Identity
In relation to that, he also wrote that Jesus bears the affliction of our condition and we enjoy the glory of his, involving an exchange not merely of status but identity. What Jesus takes to the cross is who are , our every selves with all their guilt, and what we enjoy un union with him is precisely who he is, his fullness with all its glory. This is huge. He is arguing the exchange between us and Christ on the cross, is not merely status, but identity. The identity is a big word.
In other words, we are now saved by Jesus’ condemnation by the Father. It’s really an exchange of status, and that’s what substitutional death or penal substitution’s all about. Redemption happens when Christ took our place of death, and we got life. However, he goes beyond that, he moved from status to identity. Status is the condition of our soul. But identity defines who we are, soul, and spirit. That has huge implication, because that will help us profoundly in combating against sins, as its no more we who live, but Christ who lives in us (Gal 2:20) . That verse begins to make a lot of sense now. It’s the whole Christ in us that shapes and deforms our inherit. This is easy to say, but hard to execute or implement in real life as we all know. However, the fruit of the Spirit is continually developing in our lives, as the Lord shapes and molds us by His word and His Spirit.
Gal 2:20 is best translated as “Paul, an apostle” as Paul-in-Christ. Paul-in-himself is a thing of the past. The whole identity thing if sunk into our being would a powerful of transformation in a Christian’s life, and bearing of the fruit of the Spirit. Amen.
Fostering who Christ is in us and who we are in Christ
This is a key concept and very helpful. And I like the sacraments of baptism and the Lord’s Supper as so important within the NT and frequently appealed to by Paul for this purpose.
 Grant Macaskill, Living Union with Christ, ( Grand Rapids: Baker Academic, 2019), 10
 Ligon Duncan in his lecture in the Theology of Worship class, RTS
 Ibid, 53