Yoma 86a:
שָׁאַל רַבִּי מַתְיָא בֶּן חָרָשׁ אֶת רַבִּי אֶלְעָזָר בֶּן עֲזַרְיָה בְּרוֹמִי: שָׁמַעְתָּ אַרְבָּעָה חִלּוּקֵי כַפָּרָה שֶׁהָיָה רַבִּי יִשְׁמָעֵאל דּוֹרֵשׁ? אָמַר: שְׁלֹשָׁה הֵן, וּתְשׁוּבָה עִם כׇּל אֶחָד וְאֶחָד.
Furthermore, with regard to the topic of repentance, Rabbi Masya ben Ḥarash asked Rabbi Elazar ben Azarya when Rabbi Elazar was in Rome: Have you heard the teaching that there are four distinctions in the process of atonement that Rabbi Yishmael would derive? He said to him: They are not four but three distinctions, and repentance is necessary with each one.
עָבַר עַל עֲשֵׂה וְשָׁב — אֵינוֹ זָז מִשָּׁם עַד שֶׁמּוֹחֲלִין לוֹ, שֶׁנֶּאֱמַר: ״שׁוּבוּ בָּנִים שׁוֹבָבִים״. עָבַר עַל לֹא תַעֲשֶׂה וְעָשָׂה תְּשׁוּבָה — תְּשׁוּבָה תּוֹלָה, וְיוֹם הַכִּפּוּרִים מְכַפֵּר. שֶׁנֶּאֱמַר: ״כִּי בַיּוֹם הַזֶּה יְכַפֵּר עֲלֵיכֶם מִכֹּל חַטֹּאתֵיכֶם״. עָבַר עַל כָּרֵיתוֹת וּמִיתוֹת בֵּית דִּין וְעָשָׂה תְּשׁוּבָה — תְּשׁוּבָה וְיוֹם הַכִּפּוּרִים תּוֹלִין, וְיִסּוּרִין מְמָרְקִין. שֶׁנֶּאֱמַר: ״וּפָקַדְתִּי בְשֵׁבֶט פִּשְׁעָם וּבִנְגָעִים עֲוֹנָם״.
These are the categories: If one violates a positive mitzva and repents, he is forgiven even before he moves from his place, i.e. immediately, as it is stated: “Return, you backsliding children, I will heal your backsliding” (Jeremiah 3:22), implying that when one repents he is immediately forgiven. If one violates a prohibition and repents, repentance suspends his punishment and Yom Kippur atones for his sin, as it is stated: “For on this day shall atonement be made for you, to purify you from all your sins” (Leviticus 16:30). If one commits a transgression that warrants karet or a sin punishable by death from the earthly court and then repents, repentance and Yom Kippur suspend his punishment, and suffering absolves and completes the atonement, as it is stated: “Then will I visit their transgression with the rod, and their iniquity with strokes” (Psalms 89:33).
אֲבָל מִי שֶׁיֵּשׁ חִילּוּל הַשֵּׁם בְּיָדוֹ — אֵין לוֹ כֹּחַ בִּתְשׁוּבָה לִתְלוֹת וְלֹא בְּיוֹם הַכִּפּוּרִים לְכַפֵּר וְלֹא בְּיִסּוּרִין לְמָרֵק, אֶלָּא כּוּלָּן תּוֹלִין, וּמִיתָה מְמָרֶקֶת, שֶׁנֶּאֱמַר: ״וְנִגְלָה בְאׇזְנָי ה׳ צְבָאוֹת אִם יְכוּפַּר הֶעָוֹן הַזֶּה לָכֶם עַד תְּמוּתוּן״.
But in the case of one who has caused desecration of God’s name, his repentance has no power to suspend punishment, nor does Yom Kippur have power to atone for his sin, nor does suffering alone have power to absolve him. Rather, all these suspend punishment, and death absolves him, as it is stated: “And the Lord of Hosts revealed Himself to my ears: This iniquity shall not be atoned for until you die” (Isaiah 22:14).
Chilul Hashem does not incur any punishment from the Beis Din. It is a לאו שאין בו מעשה. So how can it be worse than כריתות and מיתות בית דין???