Bah humbug is not the line you think it is
A Christmas Carol
Scrooge says "Bah! Humbug!" twice. Both times in the first few pages. He never says it again.
That is the whole design of the book and almost nobody notices, because the line escaped the novel sometime around 1870 and has been doing its own thing ever since — on mugs, on sweaters, on the sort of ornament that comes in a tin.
Dickens wrote it as a symptom. We turned it into a personality.
What he is actually objecting to
Read the exchange again. Fred invites him to dinner. Scrooge's complaint is not that Christmas is annoying — it is economic:
"What right have you to be merry? What reason have you to be merry? You're poor enough."
He is not a grump. He is a man who has decided that joy requires a balance sheet to justify it, and that anyone cheerful without money is being irrational. That is a much stranger and more modern position than "I dislike tinsel," and it is the thing the ghosts spend the rest of the night dismantling.
Why the line survived anyway
Because it is genuinely useful. There is no better two-word summary of the mood that arrives somewhere around the fourth consecutive social obligation, and it has the advantage of being a quotation — you can say it and mean it and also not quite mean it.
Which is, to be fair, exactly how Dickens' best lines tend to work.
The better line, if you want one
Marley gets it, and hardly anyone quotes it:
"Mankind was my business. The common welfare was my business; charity, mercy, forbearance, and benevolence, were, all, my business."
That is the actual thesis of the book, delivered by a dead man wrapped in cash boxes, and it is a far sharper thing to have on a wall than the noise Scrooge makes before he changes his mind.
We put the better lines on things:
Questions people ask
How many times does Scrooge say bah humbug?
Twice, both in the opening scene, and never again once the ghosts arrive. The phrase's fame comes almost entirely from outside the book.
What is Scrooge actually objecting to?
Not festivity as such. His complaint to Fred is that being merry without money is irrational — joy, to him, needs a balance sheet. That is the position the three ghosts exist to take apart.
What is the best line in A Christmas Carol?
Most readers who go back to it settle on Marley: 'Mankind was my business.' It is the book's actual argument, and it is delivered by the character with the least to gain from making it.