This is a good reminder, penned by Rabbi Steven Berkowitz in 2015.
Being grafted into the Good Olive Tree (Romans 11}, doesn't make you "Jewish" in the sense of being either replacing physical children of Israel, nor does it refer a person joining the physical people of Israel by being "grafted into the Jewish nation."
It also doesn't make you "Israel."
The Apostle Paul's statements across various letters are part of his Midrash of ancient Jewish writings (the Bible), and this that follows is what Paul is talking about:
WHO IS A JEW???
Folks. The term Jew (יהודי) did not originate with the Patriarch Judah and did not ORIGINALLY refer to his tribe or even the Southern Kingdom of Judah (and Benjamin). The term existed BEFORE Judah was born. Actually, the term means “one who praises God”. In other words, the term originally referred to anyone who rejected idol worship and sought to live a life for God in accordance with ethical and spiritual principles.
Proof of this is the fact that Judah’s great-aunt, Esau’s wife, was called Judith/Yehudit (יהודית), which LITERALLY means “Jewess” or female Jew (Genesis 26:34). This contradicts that belief that the term Yehudi BEGAN with the Patriarch Judah. (The fact that many teachers of Torah miss this is pretty scary).
The reason that all Jews are called Jews has nothing to do with us being from the Tribe of Judah or from the Southern Kingdom of Judah (and Benjamin). It means that (according to our belief) as a nation, and as individuals, we epitomize the worship and praise of God because we adhere to the Torah of Moshe.
But, again, the ORIGINAL definition includes ALL people who strive to live by spiritual principles AND worship God as being Yehudiym…praisers of God…not just those who are “Halakhically Jewish”.
Hence, the SUREST WAY of being a Jew is not being called a Jew by an Orthodox Beyth Diyn. The surest way is to live a spiritual life in devotion to God…who is Blessed forever and ever. All who follow this way is my Jewish brother or sister, regardless of their religion or lack of religion