It is not always those who externally seek to whom God gives salvation, but to those whom He calls. The Jews had been ‘seeking’ God through the Law, thinking that they could make themselves acceptable to God by good works according to the Law and to their traditions. But we see here and elsewhere in Scripture that it is not by the works of the Law that any are saved but by faith in Christ. The Gentiles, on the contrary, were called by God to faith in Christ.
Christ is a Rock of offense to those who seek salvation by their good works, but the only way of salvation is to look away from ourselves and our works, and to look to Christ Jesus entirely. It is His good works and His atoning sacrifice on the cross alone that can save.