Some argue that the doctrine of justification cannot be the heart of Paul’s gospel since justification is reserved almost entirely to two of his letters, Romans and Galatians. But this simply isn’t true. Although it is explained at greater length in those two epistles, Paul’s “justification/righteousness” theology also shows up in 1 Cor 1:30; 6:11; 2 Cor 3:9; 5:21; Phil 3:9; and Tit 3:7. These are brief statements to be sure, but their very brevity suggests that they are concise summaries of Paul’s well-known teaching.
In addition, as James Barr pointed out, the concept can be present even if the terms are absent. For example, Col 1:12 says: “joyfully giving thanks to the Father who has qualified (τῷ ἱκανώσαντι) us to share in the inheritance of the saints in the light.” In Paul’s thought, only the righteous are qualified to obtain a share in the eschatological inheritance in glory (Rom 2:7-10, 13). To say that the Father has qualified us is to imply that he treats us as righteous and therefore as fit to obtain a share in the eschatological inheritance.
Here are some of the lexicons on ἱκανόω:
LSJ: “make sufficient, qualify”
Thayer: “make sufficient, render fit”
BDAG: “to cause to be adequate, make sufficient, qualify”
It is used elsewhere in the NT only in 2 Cor 3:5-6 where Paul says that he is not sufficient/qualified in himself, but that God has made him sufficient/qualified to serve as a minister of the new covenant.
So also in Col 1:12 Paul teaches that though we are not fit in ourselves, by God’s act in Christ we have been made legally fit. The immediate context makes clear that the Father’s act of making us fit/qualified for heaven is characterized by the following:
(a) It is based on divine grace, as evidenced by the fact that Paul exhorts us to “joyfully give thanks to the Father” for so qualifying us (cf. also the explicit reference to “the grace of God” in v. 6).
(b) Being qualified for heaven is a consequence of a sovereign, divine rescue-operation (”He rescued us from the domain of darkness …” v. 13a). Lost in the guilt and bondage of sin, we could not rescue ourselves. The Father had to do it by sending his own Son as an apocalyptic inbreaking of divine power (cf. “who gave himself for our sins to rescue us from this present evil age,” Gal 1:4).
(c) We are qualified to inherit, not because of any worthiness in us, but because we have been transferred into the sphere of the very love that the Father has for his own dear Son (”… and transferred us into the kingdom of his beloved Son,” lit., “the Son of his love” [ὁ υἱός τῆς ἀγάπης αὐτοῦ], v. 13b).
(d) Our qualification to inherit is grounded in the work of Christ who redeemed us by his death and resurrection (”in whom we have redemption [ἀπολύτρωσις],” v. 14 - cf. Rom 3:24 where “redemption” is tied to justification). The accent is not on God’s work in us (sanctification) but on God’s work for us (the cross and resurrection, i.e., the atonement).
(e) We aren’t qualified to inherit because God has changed us into good people, but because of a legal transaction, namely, having the guilt of our sins wiped away (”in whom we have … the remission of our sins,” v. 14). N.B.: “forgiveness” is too weak a translation of ἄφεσις. In the LXX this term is used to refer to the complete “release/cancellation” of debts so that poor Israelite families would not lose their apportioned lot in the inheritance through debt-bondage.
Thus, Col 1:12 seems to contain all of the elements of Paul’s doctrine of justification without using the word ”justification.” And since this is the content of ”the word of the truth of the gospel” (v. 5) that Epaphras preached, we may conclude that the Father’s act of making us fit for heaven through the atoning death of Christ lies at the heart of the gospel.
I agree that Paul’s doctrine of justification is not the center of his theology. The center of Paul’s theology is the gospel of God’s Son (Rom 1:1-2), centered on the cross and resurrection of Christ (1 Cor 15:3-4). But in order to explicate what Christ has done for us in his death and resurrection, the doctrine of justification plays an absolutely essential role. The primitive Palestinian church confessed that “Christ died for our sins.” Paul the theologian came along and fleshed out what that means: He died and rose again so that the guilt of our sins might be removed and that we might be made legally fit to have a share in the inheritance.
Or to use Paul’s longer version of the primitive death-formula: “He was handed over to death [by God] for our transgressions and was raised to life [by God] for our justification” (Rom 4:25).