Calvin’s reading of the text, although it contains an element of truth, treats Abraham too much as an exemplary individual and neglects Paul’s strong emphasis on Abraham as an inclusive representative figure. We must recall that several of the “promise” texts in Genesis that are crucial for Paul’s interpretation of Abraham (e.g., Gen 12:3; 18:18; 22:18) declare that all nations will be blessed “in” Abraham. In Gal 3:8 Paul, taking the idea of participation in Abraham very seriously, quotes precisely this promise, apparently conflating Gen 12:3 with 18:18 and/or 22:18. In Rom 4 the same idea surfaces in verses 9-12 when Paul first applies the words of Ps 32:1-2 to Abraham and then asks whether this blessing (on Abraham) applies to Jews and Gentiles. The clear implication is that the blessing pronounced on Abraham applies vicariously to others who are his “seed.” This is precisely the point of view of verse 13, which regards the promise as applicable to “Abraham, or to his seed.”
In view of all this, we may begin to suspect that Rom 4:23-24 carries a similar meaning, which may be paraphrased as follows: “Scripture says, ‘Abraham believed God and it was reckoned to him as righteousness.’ However, it was not just reckoned to him as an individual: these words apply also to us (who believe in God who raised Jesus from the dead) to whom righteousness is going to be reckoned (vicariously, because we are Abraham’s seed).” This way of reading the text should not be understood as antithetical to the customary interpretation. Clearly there is an analogy between Abraham’s faith and the faith of the Christian believer; Paul chooses to stress this analogy not only in the characterization of “us” as οι πιστευοντες (v. 24) but also in his approval (v. 12) of “those who walk in the footsteps of the faith which our father Abraham had while he was uncircumcised.” The dichotomy between receiving a blessing vicariously as a result of the archetype’s faith/obedience (“in Abraham”) and receiving a blessing through reenacting the faith/obedience of the archetype (“like Abraham”) is our dichotomy, not Paul’s. Paul sees the two as indissoluble. Because we participate in the blessing pronounced upon him, we mirror his faith; because our faith parallels his, we may be said to be his seed. Paul would be content, I think, with either formulation. [The Conversion of the Imagination: Paul as Interpreter of Israel’s Scripture, 80-81]
Understood this way, the faith of Abraham relates primarily, not to the faith of the individual Christian, but to the faith of Jesus Christ. Abraham was a covenant head, just as Christ is. As Peter Leithart points out, the ordo salutis of Abraham’s life is, in many respects atypical of the regular believer. Abraham’s descendents entered into the verdict of ‘righteous’ proclaimed over Abraham. Isaac received the seal of the righteousness of faith as an infant. The justification of Abraham’s descendents was dissimilar in many respects to Abraham’s own. It was an entering into Abraham’s righteous status as they entered into his faith.
The same is true of the new covenant believer. We enter into the faith of Jesus Christ and the status of righteous given to Him at the resurrection. Entering into the faith of Jesus Christ involves both the receiving of a blessing vicariously and the reenacting of Christ’s own faith by the power of the Spirit.
This is one of the truths that N.T. Wright tries to uphold in his doctrine of justification. God sees faith and declares that the person is forgiven and a member of the family promised to Abraham. Wright wants to retain both the fact we are declared righteous because we enter into the verdict declared over Christ and vicariously receive His blessings through faith and the fact that we are declared righteous because by the new life of the Spirit the believer reenacts Christ’s faith in his own life.