I actually agree with a lot of this: if you look at the next post, you'll see my thoughts about atheism are "it's not actually a priority at all." (All the topics listed there are not necessarily ones that should be included, just ones that have played some role historically)

That said, I'm also defining subthemes a bit differently than you. For example, if I were making a similar list for Christmas, it'd be:

Generosity
Peace on Earth, Goodwill
Theological Birth of Christ
The Nativity Scene (i.e. Mythological Birth of Christ)
King Herod et all
Family
Winter Festivities / Winter Wonderland
Santa Clause (and Christmas Magic) Christmas Candy/Food (candy canes, gingerbread, etc)

It's not just about the core-themes, it's about the surrounding mythology that springs up around those core themes. Several of the things I just listed also have a lot of sub-components.

The mythology is going to evolve over time, but I do think it's important to give it a strong definition early on, because that can shape how it further evolves over time.