chinuch in emunah

After cheit ha'eigel Hashem the Torah reiterates its warning against avodah zarah (34:11-17) and then continues with the mitzvah to observe Pesach

אֶת־חַ֣ג הַמַּצּוֹת֮ תִּשְׁמֹר֒ שִׁבְעַ֨ת יָמִ֜ים תֹּאכַ֤ל מַצּוֹת֙ אֲשֶׁ֣ר צִוִּיתִ֔ךָ לְמוֹעֵ֖ד חֹ֣דֶשׁ הָאָבִ֑יב כִּ֚י בְּחֹ֣דֶשׁ הָֽאָבִ֔יב יָצָ֖אתָ מִמִּצְרָֽיִם׃

and later in the same parsha, the other moadim:

 וְחַ֤ג שָׁבֻעֹת֙ תַּעֲשֶׂ֣ה לְךָ֔ בִּכּוּרֵ֖י קְצִ֣יר חִטִּ֑ים וְחַג֙ הָֽאָסִ֔יף תְּקוּפַ֖ת הַשָּׁנָֽה׃

The mitzvah of observing the moadim appeared already in parshas Mishpatim.  Why repeat it again in this context and juxtapose it to the warnings against avodah zarah?

I wonder if it is because of Aharon's call of "chag la'Hashem machar" when he asked for donations for the eigel.  If making an eigel is what you think a "chag la'Hashem" is, then you need a reminder on what the real chagim are all about.

Netziv answers that in addition to the moadim being an opportunity for celebration, they are an opportunity to inculcate emuna.  They therefore stand as a bulwark against the practice of idolatry, which is the theme of the parsha.

 לא בא הכתוב לבאר שלש רגלים, שכבר כתיב לפני מעשה העגל (לעיל פרק כ״ג), אלא בא בהוספת ענין להזהיר בדרך מוסר ולעשות מסילות בלב ישראל בזמנים הללו להשריש בהם יראת ה׳ ואמונה

He quotes that Chazal darshen that command to observe Shavuos and Sukkos in our parsha teach us that even during shemita year these holidays must be observed.  Even though the normal cycle of planting and harvesting and the celebrations that go along with those agricultural milestones are interrupted during shemita, the  moadim are still observed because they serve as a time of reflection to work on emunah.

Aruch haShulchan writes at the end of 472

ולכן צריך ליתן כוס לכל אחד מבני ביתו, הן זכרים הן נקיבות. ואפילו תינוקות שהגיעו לחינוך – מצוה ליתן לכל אחד כוסו לפניו...

ולפני תינוקות – אין קפידא. ויראה לי דאף על גב דבכל מקום אין הבנות בכלל חינוך, מכל מקום בליל פסח צריך לחנכן גם כן, מפני שעיקר האמונה תלוי ביציאת מצרים.

Even though there is no chiyuv chinuch m'din 4 kosos for tinokos, there is a din chinuch for the mitzvah of emunah.  When you sit at the seder it's just the particular mitzvos of matzah, 4 kosos, etc. that you are teaching your children about, but it's about belief in Hashem and his power to intervene in history.

(Earlier in the week I mentioned the chiddush if the Raavyah that even children below the age of chinuch for megillah should hear it read because af hein hayu b'oso ha'nes of the threatened destruction.  I am wondering if the same would hold true for the mitzvos of leil ha'seder.  In any case, I think many ketanim would be unable to drink 4 cups of wine, in which case maybe there is no chiyuv chinuch given that the mitzvah cannot be fulfilled is its proper tzurah (same issue as giving a katan a pasul lulav for the sake of chinuch.)

It's not just the chag itself.  Netziv is medayek that in Mishpatim the pasuk writes לְמוֹעֵד֙ חֹ֣דֶשׁ הָֽאָבִ֔יב כִּי־ב֖וֹ יָצָ֣אתָ מִמִּצְרָ֑יִם -- it is the day, ב֖ו, which is the focus.  In our parsha, where the celebration of moadim is a kiyum in working on our emunah, the pasuk ends  כִּ֚י בְּחֹ֣דֶשׁ הָֽאָבִ֔יב יָצָ֖אתָ מִמִּצְרָֽיִם It's not just a specific day, but it's the entire month of Nisan which is an auspicious time to work on one's emunah.

Aruch haShulchan 429:13 - 

ואין לשאול: איזה יחוס יש להימים שאחר הפסח? דיש לומר: הואיל שיצא רוב החודש בקדושה (מגן אברהם סעיף קטן ג). ובאמת אין צורך לזה, דכל חודש ניסן קדוש, מפני הטעמים שבארנו.