"But when God, who set me apart from birth and called me by his grace, was pleased to reveal his Son in me so that I might preach him among the Gentiles, ..." (Gal 1:15, 16a NIV).
It may be argued by some that the Isaiah (49:1-6) passage is speaking in context of Israel, YHWH's servant, with ultimate fulfillment in Jesus Christ, the Suffering Servant of Isaiah 52:13-53:12. Therefore the Apostle Paul would not claim himself to be "a light for the Gentiles" (Isa 49:6). They would be right on the first account, ...