Interesting points for sure. Though I did not mean celebrate as done commercially with Christmas but the religious importance of it.

Orthodox Christianity is very much Roman, very much eastern Roman aka. Byzantine (arguably more so than Roman Catholics and much more than whatever Protestants are doing LOL) and Pascha (Easter) is the most important religious holiday there is.

You prepare for it by fasting for 40 days (and I mean seriously, like not just “I won’t eat candy or meat”, but basically a vegan diet with some days even having restrictions on certain vegetable oils etc.) and then break the fasting (with the eggs, baked goods and whatever is traditional for your region that you brought to be blessed the day before) after partaking in night liturgy and most importantly a procession around your church.

I grew up with the ex-soviet light variant of this (as in real fasting, but not the full on-night liturgy and we skipped a lot of the weekday liturgies and preparations during the Great Fast), but we did have Butter Week before the Great Fasting :)

(Also I’m skipping a lot of details in this comment)