For as ye - You who were Gentiles.
In times past - Before the gospel was preached. This refers to the former idolatrous and sinful state of the pagan world; compare Ephesians 2:2; Acts 14:16.
Have not believed God - Or have not obeyed God. This was the character of all the pagan nations.
Yet have now obtained mercy - Have been pardoned and admitted to the favor of God.
Through their unbelief - By means of the unbelief and rejection of the Jews; see the note at Romans 11:11.

For as ye in times past - The apostle pursues his argument in favor of the restoration of the Jews. As ye, Gentiles, in times past - for many ages back.
Have not believed - Were in a state of alienation from God, yet not so as to be totally and for ever excluded,
Have now obtained mercy - For ye are now taken into the kingdom of the Messiah; through their unbelief - by that method which, in destroying the Jewish peculiarity, and fulfilling the Abrahamic covenant, has occasioned the unbelief and obstinate opposition of the Jews.

(16) For as ye in times past have not believed God, yet have now obtained mercy through their unbelief:
(16) Another reason: because even though they who are hardened are worthily punished, yet this stubbornness of the Jews has not so that there would be a hatred of that nation, but so that an entry might be as it were opened to bring in the Gentiles, and afterward the Jews being inflamed with jealousy of that mercy which is shown to the Gentiles might themselves also be partakers of the same benefit, and so it might appear that both Jews and Gentiles are saved only by the free mercy and grace of God, which could not have been so manifest if at the beginning God had brought all together into the Church, or if he had saved the nation of the Jews without this interruption.

For as ye in times past have not believed God,.... The times referred to, are the times of ignorance, idolatry, and superstition; when God suffered the Gentiles, for many hundreds of years, to walk in their own ways; while the Jews were his favourite people, were chosen by him above all people, separated from them, and distinguished by his goodness; had his word and oracles, his judgments and his statutes to direct them, and many other valuable blessings: the times before the coming of the Messiah are here meant, when these people sat in darkness, and in the region of the shadow of death; till Christ, who came to lighten the Gentiles, sent his Gospel among them, and which has been attended with great success; in these times they were in a state of incredulity: they either, as some of them, did not believe there was a God, or that there was but one God, at least but very few believed it; and these did not know who he was; nor did they glorify him as God, or perform any true spiritual worship to him: the far greater part believed there were more gods, and did service to them which by nature were no gods, and fell down to idols of gold, and silver, and wood, and stone:
and yet have now obtained mercy through their unbelief; that is, they were regenerated, effectually called and converted, through the rich and abundant mercy of God; repentance unto life was granted to them; and faith in our Lord Jesus, as a free grace gift, was bestowed upon them; and they had an application of pardoning grace and mercy, through the blood of Christ, made unto them; and all this through the unbelief of the Jews: not that their unbelief could be the cause of their obtaining mercy; but the Jews not believing in the Messiah, but rejecting him, and contradicting and blaspheming his Gospel, it was taken away from them, and carried to the Gentiles; which was the means of their believing in Christ, and obtaining mercy; so that the unbelief of the Jews was the occasion and means, in Providence, of bringing the Gospel to the Gentiles, whereby faith came; see Romans 11:11. This mercy they are said to enjoy "now"; for the present time of the Gospel is the dispensation of mercy to the Gentiles.

For as ye in times past have not believed--or, "obeyed"
God--that is, yielded not to God "the obedience of faith," while strangers to Christ.
yet now have obtained mercy through--by occasion of
their unbelief--(See on Romans 11:11; Romans 11:15; Romans 11:28).