The Power of Kaddish
“Rabbi Yehoshua son of Levi said: He who responds [during the recital of Kaddish], ‘May His great Name be blessed forever and eternity’ with all his כֹּחַ (koaḥ), might, his [heavenly] decreed sentence is torn up… Resh Laqish said: He who responds אָמֵן (amen) with all his כֹּחַ (koaḥ), might, has the gates of the Garden of Eden opened for him, as is written, Open the gates, that the righteous nation which keeps faithfulness may enter in (Isaiah 26:2)—do not read שֹׁמֵר אֱמֻנִים (shomer emunim), keeps faithfulness, but שֶׁאוֹמרִים אָמֶן (she’omrim amen), that say, אֶמָן (amen). What does אָמֵן (amen) mean? Rabbi Ḥanina said: אֶל מֶלֶך נֶאֶמָן (el melekh ne’eman), God faithful King” (BT Shabbat 119b).
“Come and see: This Kedushah is not like other Kedushot, which we triple. Rather this Kedushah ascends on all sides above and below, in all aspects of Faith, smashing locks and seals of iron and evil shells, so that the glory of the blessed Holy One will be exalted above all. We must recite it in the language of the Other Side [namely, Aramaic], and respond with mighty כֹּחַ (koaḥ), power: ‘Amen! May His great Name be blessed,’ so that the power of the Other Side is broken, the blessed Holy One ascends in glory and remembers His children and remembers His Name. Since the blessed Holy One is exalted in His glory by this Kedushah, it must be uttered only in the presence of ten” (Zohar 2:129b).
“The enlightened—they know the letters, of them it says ‘[Rav Yehudah said in the name of Rav:] Bezalel knew how to combine the letters by which the heavens and earth were created’ (BT Berakhot 55a) [cf. Zohar 2:152a]. They are the כ״ח (twenty-eight) letters [and seven words], and another fourteen are hidden within them: בְּרֵאשִׁית בָּרָא אֱלֹהִים אֵת הַשָּׁמַיִם וְאֵת הָאָרֶץ (bereshit bara elohim et ha-shamayim ve-et ha-erets), In the beginning God created the heavens and the earth (Genesis 1:1), of which is said, the כֹּחַ (koaḥ), power, of His deeds He told His people (Psalms 111:6). But at the time of the exile, these כ״ח (twenty-eight) letters departed, as is said: And they have gone without כֹחַ (khoaḥ), strength, before the pursuer (Lamentations 1:6). Therefore, it is said in [the introduction to] Kaddish, ‘And now, may the כֹּחַ (koaḥ), power, of the Lord be magnified,’ corresponding to כ״ח (twenty-eight) other letters that form seven words, which are יְהֵא שְׁמֵהּ רַבָּא מְבָרַךְ לְעָלַם וּלְעָלְמֵי עָלְמַיָּא (yeheh shemeh rabba mevarakh le-alam ul-alemei alemaya), ‘May His great Name be blessed forever and eternity.’ Thus, the statement, ‘Whoever answers May his great Name… with all his כֹּחַ (koaḥ), might, becomes a partner with the blessed Holy One in the act of Creation and the giving of the Torah’ (BT Shabbat 119b). The other י״ד (fourteen) are the name יְהוָה אֱלֹהֵינוּ יְהוָה (Adonai Eloheinu Adonai), YHWH our God YHWH (Deuteronomy 6:4). The hint is the night before the fourteenth [of Nisan, i.e., Passover] we check for חָמֵץ (ḥamets), leavend bread, by the light of a candle, with these י״ד (fourteen) letters as He swore, כִּי יָד עַל כֵּס יָהּ (ki yad al kes Yah), For hand upon Yah’s throne [War for YHWH against Amalek from all time] (Exodus 17:16)” (Tiqqunei ha-Zohar 13a).