In his chapter on the theology of Paul, he discusses the importance of obedience, the nature of Paul's indicatives (what has been done for us and who we now are) and imperatives (commands), and the impact of the already-but-not-yet nature of the kingdom. I found this discussion immensely helpful.
Another illustration of the indicative and imperative occurs in Rom. 6. Believers have died to sin in baptism, for they have died with Christ and will be raised with him. Because they are united with Christ, they share his victory over sin and death. The "old person" (Rom. 6), the old Adam, has been crucified with Christ, who is the new person (Eph. 2:15). Sin's tyranny and dominion have been dethroned. Believers have a new Lord and a new king, and sin is no longer the master, since they are united with Christ. The indicative is that believers have died to sin, and the power of the resurrection is now theirs. The death of the old person in Adam matches what Paul teaches in Colossians. Believers "have put off the old self with its practices" (Col. 3:9), and they have put on the new person (Col. 3:10).
And yet Paul commands believers "to put off your old self" (Eph. 4:22) and "to put on the new self" (Eph. 4:24). The old person has been crucified with Christ, and yet the old self must still be put off. Thus, believers are "to put on the Lord Jesus Christ" (Rom. 13:14). Perhaps we see a hint in Colossians of the tension between the old and new person, for even though believers have put on the new person, there is a process of renewal in the image of the creator (Col. 3:10). As we saw in Rom. 6:1-10, believers have died to sin, but they must count themselves as "dead to sin and alive to God in Christ Jesus" (Rom. 6:11). They must not let sin "reign" in their bodies or "obey its passions" (Rom. 6:12). They must give their members to God (Rom. 6:13). If they present their members to sin, they will face eternal death (Rom. 6:16, 23). The threat in the imperative is quite remarkable. Obedience is not optional. Those who give themselves over to sin will not enjoy eternal life. Once again, the imperative stands forth in all its starkness, showing that the new life of believers is no abstraction. And yet the imperative is grounded in and even secured by the indicative. After the stirring commands in Rom. 6:11-13, we read in 6:14, "For sin will have no dominion over you, since you are not under law, but under grace." This is not a command; it is a promise. On the one hand, believers are exhorted to pursue obedience lest they die; on the other hand, they are promised that they will not surrender to evil, for the grace that has captured them will triumph...
...The kingdom has come, and believers must live under the rule of their king. Paul teaches that the Holy Spirit empowers and transforms Christians so that they are enabled to please God. Paul does not teach perfectionism. The "already but not yet" persists. There is a tension between the indicative and the imperative. The indicative reflects what God has accomplished for believers in Christ; the imperative call upon believers to live upon the basis of the indicative. They are to be what they are. They are to be now what they will be on the last day. The last days have arrived. Believers are no longer under the Torah, for the Mosaic law was temporary and never was intended to be permanent. The new covenant, now present on the basis of the cross and the resurrection of Jesus Christ, is marked by the gift of the Holy Spirit. believer are to follow the law of Christ and are to love as Christ did. Obeying the moral norms that reflect God's character should mark their lives, as they live in dependence upon the Holy Spirit.
Tom Schreiner, The King in His Beauty, pages 566-7, 571