Paul did not take the message of Jesus the Messiah to the Gentiles out of mere frustration that his fellow Jews had refused it, as a kind of displacement activity, but rather out of the conviction that, if God’s purposes for Israel had indeed now been fulfilled, it was time for the Gentiles to come in. As becomes increasingly clear, his Gentile mission was an eschatological activity—that is, a task to be undertaken once God had acted climactically and decisively within history. It was a key feature of the new age that had now dawned, part of Paul’s sense that God’s future had arrived in the present, in the person and achievement of Jesus and the power of the Spirit. Although Paul clearly believed that there was a further and final event still to come, which he describes variously at different points in his writings, the great promised “end” had already begun to happen (see particularly 1 Cor 15:20-28).
N. T. Wright, “Romans.” NIB: 401-02.