The only "identity" Jєωs today have is cultural.
So, St. Paul most likely means all the biological seed of Abraham will convert in the end times? Yet, this doesn't seem to agree with Romans 9:6: "all are not Israelites that are [biologically] of Israel."
How does the Church determine who is a Jєω? Is a Jєω nowadays simply whoever claims to be a Jєω?
A more explicit rendition of the consideration might have been "The
most common means of identification by which Jєωs are distinguished is cultural." A
mea culpa for my imprecision.
I would suggest consulting Jєωιѕн sources for whom they consider to be Jєωs and under what circuмstances they accept "converts".
It's been more than 40 years since I took courses in New Testament theology under the Jesuits and I am too rusty to hanker a guess at the interpretation of the passage from Romans. So, these days, I rely on sound commentaries, like this one from Haydock:
"Ver. 6-7. Not as though the word of God hath failed in his promises made to Abraham, and the patriarchs. The Jєωs pretended that the promises were made to them only, and to those that were of their race, and that the Gentiles were not to partake of them. St. Paul shews them their mistake, by telling them who are to be esteemed the true children of Abraham, and of the patriarchs, according to the promises which God made, and who are not. (Witham) ---
All are not Israelites, &c. Not all, who are the carnal seed of Israel, are true Israelites in God's account: who, as by his free grace he heretofore preferred Isaac before Ismael, and Jacob before Esau, so he could, and did by the like free grace, election, and mercy, raise up spiritual children by faith to Abraham and Israel, from among the Gentiles, and prefer them before the carnal Jєωs. (Challoner) --- Neither are all they, who are of the seed of Abraham, his true spiritual children, to whom these promises were made: nor are all they who are descended from Isaac the children of these promises nor are all they true Israelites, to whom these blessings were promised, although they are descended from Israel; but only they who are the children of the patriarchs by faith in Jesus, the Messias, in whom God promised that he would bless all nations. (Witham)
http://haydock1859.tripod.com/I hope those responses are helpful.