I really don't think that HN is the place for pushing one's own dogmatic definition of Christianity. The people who celebrated Halloween have always considered themselves to be Christian, and there's no logical reason to give preference to your definition of the religion over theirs.

I have no problem with you having strong opinions about what the Bible teaches (I have similarly strong opinions myself!), but arguments about what counts as Christian invariably turn on dogma alone, which kills curiosity.

In Catholic tradition, which predates sola scriptura, the Bible gets legitimacy from the church, which predates the Bible, not vice versa.

The idea that the Bible ought to be the only source of Christian teaching is a very new idea. The apostolic churches don't buy it.

Not to say it's right or wrong but there's a two thousand year array of evidence that this is how the Catholic Church sees things.

From your reference to "the apostolic churches" I assume that you understand this, but to clarify for any less familiar with Christian denominations: both the Roman Catholic and the Orthodox churches (between them representing about 60% of global self-identifying Christians) deny the supremacy of the Bible for the same reason.

As someone on the OrthodoxChristianity subreddit put it [0], "show me where the table of contents comes from." Both Orthodox and Catholic Christians believe that because the list of books that make up the Bible is an output of some combination of history, tradition, and church councils, it can't be treated as superior to them.

[0] https://old.reddit.com/r/OrthodoxChristianity/comments/14y7f...

It came from Protestants pretending not to be Catholic, actually

Catholics and Protestants both have their own ways of pretending to be Christian while ignoring teachings in the bible. (though protestant has enough different sects that you can't draw a blanket on any one thing that they all do wrong)

Have you read much about the history of Catholicism and Protestantism? It sounds as if you’re speaking a bit out of your depth, admittedly.