I assume you mean Jews converted by God to faith in Jesus Christ as [Thomas put it] "my Lord and my God".
It is not as though the Word of God hath taken no effect. For they are not all Israel, who are of Israel; neither because they are the seed of Abraham are they all children; but, "In Isaac shall thy seed be called." That is, they who are the children of the flesh, these are not the children of God; rather, the children of the promise are counted as the seed.