God’s answer to Paul’s prayer in 12:9a and Paul’s response in 12:9b–10 form the conclusion both to Paul’s experience of his thorn in the flesh (vv. 7b–8) and to his refraining from boasting in his own “surpassingly great revelations” (vv. 5–7a). Instead of removing the thorn, Christ declared that his own grace would be sufficient for Paul in the midst of his suffering, for his weakness would provide the platform for perfecting the Lord’s power (v. 9a).

Paul’s sufferings can never outstrip God’s supply of grace (cf. 1:8–11). For this reason, he will “all the more gladly” boast in his weaknesses instead of his revelations, in order that the power of Christ may dwell on him (v. 9b; cf. 1:9–10; 11:30; 12:5). The promise of God’s grace and power leads Paul to be pleased in his sufferings (v. 10a) rather than continuing to pray for their removal, because he now knows that “when” he is weak, “then” he is strong (v. 10b). Thus, the revelation of Christ’s power in Paul’s weakness (v. 9b) and Paul’s consequent contentment (v. 10a) form the high point of his argument in this passage and, in doing so, provide a summary of the theological substructure of 2 Corinthians as a whole. To comment on these verses in our words is to risk detracting from their own profundity.

The contrast between Paul’s thorn and God’s word of grace is yet another expression of the principle established in Jeremiah 9:23–24 and applied to Paul’s ministry in 10:17–18. In 10:17–18 “boasting in the Lord” referred to Paul’s apostolic ministry of the Spirit (cf. 3:1–3), whereas in 12:9–10 it refers to Paul’s suffering (cf. 2:14–17). Just as his founding of the church in Corinth is a boast in the power of God’s Spirit, so too his ministry in the midst of weakness is a boast in the power of God’s grace (note the parallel between grace and power in 12:9; cf. 4:7–12; 6:3–10). Paul’s weakness makes it clear that his apostolic ministry, in all its glory, can only be attributed to the Lord (1:12; 3:4–6; 5:14, 18; 10:8).

Paul is a jar of clay (cf. 4:7). His weakness is the occasion for God’s sufficient grace and power. His reference in 12:9 to “Christ’s power … resting on me” recalls the earlier affirmation in 3:7–18 that under the new covenant the glory of God is being revealed in Christ “unveiled.” Here too Paul is reflecting the contrast between his own ministry of the Spirit and the veiled glory on Moses’ face and in the tent of meeting, tabernacle, and temple (cf. Ex. 25:8; 40:34; Ezek. 37:27; John 1:14; 2 Cor. 6:16; Rev. 21:3). Christ’s declaration and Paul’s response in 12:9 are yet another affirmation that the apostle is a mediator of God’s transforming presence under the new covenant ministry of the Spirit.

Instead of calling that ministry into question, Paul’s various weaknesses (listed in 11:23b–33 and now summarized in 12:10) are therefore his only legitimating boast as an apostle, since they are the means by which God makes known his glory in Christ among the Corinthians (cf. 1:3–11; 2:14–16a; 3:7–4:6; 4:13–18). For this reason, Paul boasts in the very things that cause others to slander him. His strength in 12:10b is not his personal strength, but the strength that derives from his divinely granted ability to endure adversity for the sake of the gospel (cf. 4:7–18). This then is Paul’s strongest argument for the legitimacy of his apostleship: His weaknesses are the basis of Christ’s power. For to boast in his weakness (11:30; 12:5, 9–10) is, at the same time, to boast in what the Lord is doing by his grace and power (Jer. 9:22–23).