"There is a story in the Talmud of a man who went to Babylon and had reason to ask for some help with something.
The Jews there did not come to his assistance, either with money or anything else.
The man, in describing them, wrote 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."
From Pebbles of Wisdom from Rabbi Adin Steinsaltz (forthcoming)