JUDAISM IS… ahavat yisrael -the love of Israel.
Contrary to the belief of the world; Judaism is not simply a religion. The Torah describes the Jewish people as a single unified soul that emerged from Ya’aqov.
Sh’mot 1:5
וַֽיְהִי כָּל־נֶפֶשׁ יֹצְאֵי יֶֽרֶךְ־יַעֲקֹב שִׁבְעִים נָפֶשׁ
And all the persons [lit: The entire Soul] who [that] emerged from Ya’aqov’s loins were seventy souls [lit: Soul]…
Prior to entering the land, in Parashat Nitzavim, Moshe assembled the Jewish people together to make them understand that their covenant with HaShem is based upon עריבות (Accountability).
D’varim 29:9-12
אַתֶּם נִצָּבִים הַיּוֹם כֻּלְּכֶם לִפְנֵי יְהוָה אֱלֹהֵיכֶם רָאשֵׁיכֶם שִׁבְטֵיכֶם זִקְנֵיכֶם וְשֹׁטְרֵיכֶם כֹּל אִישׁ יִשְׂרָאֵֽל׃ טַפְּכֶם נְשֵׁיכֶם וְגֵרְךָ אֲשֶׁר בְּקֶרֶב מַחֲנֶיךָ מֵחֹטֵב עֵצֶיךָ עַד שֹׁאֵב מֵימֶֽיךָ׃
לְעָבְרְךָ בִּבְרִית יְהוָה אֱלֹהֶיךָ וּבְאָלָתוֹ אֲשֶׁר יְהוָה אֱלֹהֶיךָ כֹּרֵת עִמְּךָ הַיּֽוֹם׃ לְמַעַן הָקִֽים־אֹתְךָ הַיּוֹם׀ לוֹ לְעָם וְהוּא יִֽהְיֶה־לְּךָ לֵֽאלֹהִים כַּאֲשֶׁר דִּבֶּר־לָךְ וְכַאֲשֶׁר נִשְׁבַּע לַאֲבֹתֶיךָ לְאַבְרָהָם לְיִצְחָק וּֽלְיַעֲקֹֽב׃
You are standing today, all of you, before HaShem, your G-d: the heads of your tribes, your elders, and your officers – all the men of Yisrael; your small children, your women, and your gerim who is in the midst of your camp, from the hewer of your wood to the drawer of your water, for you to pass into the covenant of HaShem, your G-d, and into His imprecation that HaShem, your G-d seals with you today, in order to establish you today as a people to Him and that He be a G-d to you, as He spoke to you and as He swore to your fathers, to Avraham, to Yitzhaq, and to Ya’aqov.
The reason why Moshe listed every person in Jewish society while using the superfluous expression; אַתֶּם נִצָּבִים הַיּוֹם כֻּלְּכֶם (You are standing today, all of you) is to teach every Jew that they are responsible for their fellow Jew. From this pasuk (verse), Chazal taught; כל ישראל ערבים זה בזה, all Jews are responsible for one another (Bavli, Shavuot 39a). This means that Judaism is not just a religion. Judaism is a soul. A single soul radiating into many bodies, each ray shining forth on its unique mission, each body receiving the light according to its capacity, each embodiment playing its crucial role. Together, each Jew compose a symphony with no redundant parts, no instrument more vital than another. And our path back towards that original source of light is through every other ray that extends from it.
Ahavat Yisrael is based upon the mitzvah to unconditionally love every Jew no matter where they are at in life:
Vayiqra 19:17-18
לֹא־תִשְׂנָא אֶת־אָחִיךָ בִּלְבָבֶךָ הוֹכֵחַ תּוֹכִיחַ אֶת־עֲמִיתֶךָ וְלֹא־תִשָּׂא עָלָיו חֵֽטְא׃ לֹֽא־תִקֹּם וְלֹֽא־תִטֹּר אֶת־בְּנֵי עַמֶּךָ וְאָֽהַבְתָּ לְרֵעֲךָ כָּמוֹךָ אֲנִי יְהוָֽה׃
You shall not hate your brother in your heart; you shall reprove your fellow and do not bear a sin because of him. You shall not take revenge and you shall not bear a grudge against the members of your people; you shall love your fellow as yourself – I am HaShem.