The Inner Jewish Spark that Cannot be Extinguished
Rav Kook explains that there are people whose Jewish segulah is not seen or felt at all, to the point where he could be mistaken for a total Gentile. However, Rav Kook emphasizes, this can only happen to one who has developed a hatred for his Jewish brethren – but that even in this case, his segulah is still there
Segula: Part 1: What is Emuna?/When Are We Called "Children" of G-d?
There are various levels of faith. Jewish faith - emuna - is different than other faiths. Emuna refers not just to a sense of belief, but rather to a connection with Hashem (G-d), and it is via this connection that a Jew directs his life and actions in the world...The very link between the Nation of Israel and Hashem is totally different from that between the rest of humanity and the Divine...
The uniqueness of the People of Israel does not begin with the appearance of the people of Israel, but well before that. As R. Yehuda HaLevy says in his classic work HaKuzari, we already see differences between people starting from the days of Adam HaRishon – the first human being to live on the face of the earth – and we comprehend that not everyone is equal.