A person of Israel is said to be born with three basic qualities:
Pity, shyness, and kindness.
And it cannot be explained by comparing greater or lesser individuals, or even by pointing to generations of teaching.
It is something that every Jew has, a character structure which belongs to the paradigm of Israel.
Thus, a person who does not exhibit these qualities is said to be not of the seed of Abraham, Isaac, and Jacob-even though he may be a proper Jew in the sense that he performs the mitzvot.
There is a story in the Talmud of someone who went to Babylon and asked for help.
The Jews there did not come to his assistance, either with money or anything else, and he wrote saying that these were evidently not Jews, but a mongrel community, because they failed to show kindness.
He did not inquire whether they prayed or put on tefillin or wore tzitzit.
The fact that they did not act naturally and spontaneously with kindness was decisive.
–Rabbi Adin Steinsaltz
From The Long Shorter Way, p. 6, by Rabbi Adin Steinsaltz