Forgiveness (13-14): Paul here continues his rationale for our submission to Christ alone (2:6, 8).[1] In addition to the imagery of burial and resurrection in 2:12,[2] our conversion is now depicted in terms of death and life. While we were spiritually dead,[3] the Father[4] made us spiritually alive with Christ. And this transformation came about through the total forgiveness of sins ("all our transgressions"). The Father cancelled out all of our spiritual debt so that there is no further need for payment for sin (cf. Hebrews 10:10-14). With the powerful imagery of the crucifixion, this certificate of debt is pictured as being nailed to the cross. In Christ, we have been given a new life with a clean slate.
Freedom and Victory (15): Paul then returns once again to the topic of the spiritual realm.[5] Through Christ, the Father vanquished the evil forces so that they have suffered a devastating defeat,[6] and we are totally freed from their power. As a people who belong to Christ, who is "the head over all rule and authority" (2:10), we need not be intimidated by demonic powers. We are of God; His Son keeps us, and the evil one does not touch us (1 John 5:18-19).
[1] This explanation begins in 2:9 ("For in Him"). We submit to Christ's supreme authority, free from all others.
[2] ESV and NKJV begin 2:13 with "And" (omitted by NASB). Paul continues to speak of our new life in Christ.
[3] Paul also describes spiritual deadness in terms of "the uncircumcision of your flesh." The word for uncircumcision here (a-kro-bu-sti-a [ἀκροβυστία]) is unrelated to the word used earlier in 2:11 (pe-ri-to-mē [περιτομή]). This verse speaks of the readers' Gentile heritage. As Gentiles, they were separated from God's covenant with Israel with no access to God. Spiritual deadness relates to both sin and separation from God.
[4] The Father is the subject in these verses with Christ playing a different role than the subject: "He [the Father] made you alive together with Him [Christ]" and "He [the Father] … nailed it to the cross [where Christ suffered]" and "He [the Father] made a public display… having triumphed over them through Him [Christ]."
[5] 2:15 starts with no conjunction and breaks away from the topic of conversion (2:11-14). But this does not introduce a brand new thought, as Paul had previously alluded to this topic of spiritual forces in 2:10 ("all rule and authority "). Cf. also 2:8 ("elementary principles of the world") and 1:16 ("rulers or authorities").
[6] "Disarmed" and "triumphed over" speak of this defeat. We see this in Jesus' ministry (Luke 10:17-18; cf. Mark 1:22-27, 34; 5:1ff.; 7:24ff.) and His death (Heb. 2:14-15). Cf. also Rev. 20:10 for Satan's final judgment.