Mordechai was mainly called a Yehudi (i.e., from Shevet Yehuda) and not a Yemini (from Shevet Binyamin). His mother descended from Shevet Yehuda, and because Dovid (from Shevet Yehuda) saved his Zeide’s life (Shim'i ben Gera), he owed his existence to Yehuda, and therefore he is called “Ish Yehudi” (Chazal). Notice that it never says Hashem’s name in the Megila. This is Mordechai’s story, and we never see his mentioning Hashem’s name.
This is unlike Yosef, upon whom it says: שֵ ם שָ מַ יִ ם שָ גור בְּ פִ יו רש"י וישב לט ג the name of Hashem was always on his lips; indeed the Torah is loaded with Yosef always mentioning Hashem’s name. But by the stories of Yehuda, not once do we find him mentioning Hashem’s name! Chazal say that since Yosef was M’kadesh Shem Shamayim in private, therefore he had one letter of Hashem’s Name (Heh) added to his name (and was called: יהוֹסֵף “Yehosef”). But Yehuda was M’kadesh Shem Shamayim in public, his entire name is the name of Hashem.
At the end of the Megila it says that Mordechai was: וְּרָצוי לְּרֹב אֶחָיו אסתר י ג liked by MOST of his fellow Jews, and the: מַ הַ רִ "י קָ רָ א says that there were some Yidden who had Taynos on Mordechai for not bowing down to Haman and causing the whole Tzara. Why did Mordechai do this? (see R' Desler Zatzal). The answer is that Mordechai HaYehudi was in a different world. He was on the level of “his entire name is the name of Hashem”.
He wasn’t involved in “cause-and-effect” like the rest of the world. He viewed not-bowing-down to Haman as the greatest Zechus and Tikkun, especially since the true reason for the Gezeira of Haman was because 1. they were Nichshal in: שֶנֶּה נו מִסְּעודָתוֹ שֶל אוֹתוֹ רָשָע enjoying the Seuda of that Rasha, and 2. מִפְּנֵי שֶהִשְּתַחֲוו לַצֶלֶם בִ יְּ מֵי נְּ בוכַ דְּ נֶ צַ ר מגילה יב א bowing down to the statue of Nevuchadnetzar. So Mordechai undoes their evil, by 1. not partaking in Seudas Achashverosh, and 2. not bowing down to the Avoda Zara of Haman.
All his actions are totally Hashem, and perhaps this is why he is constantly called “HaYehudi”. Similarly, we find: וַיִגַש אֵלָיו יְּהודָה where Yehuda pleaded with Yosef to save Binyamin, yet, his entire name is the name of Hashem.
