In "A Christmas Carol", what reason does Scrooge give for not joining his nephew at Christmas?
First, Scrooge basically says that he does not like Christmas, and so he has no desire to celebrate it. He describes it as the following:
"a time for paying bills without money; a time for finding yourself a year older, and not an hour richer; a time for balancing your books and having every item in 'em through a round dozen of months presented dead against you."
In other words, Scrooge seems to feel that this is a time not only when people are financially irresponsible, spending money they do not have, but also, by extension, that this is a generally unprofitable time for individuals in general. Scrooge values money, and Christmas, to him, is just a time to spend money, so he does not like it. He does not place value on family, relationships, compassion, love, and so forth, and these things might compel him to go to Fred's house; he only values wealth, and Christmas depletes it, so he will not go on principal. Christmas is a celebration of lots of things, but money is not one of them.
Furthermore, Scrooge seems to change the subject when he asks, "'Why did you get married?'" However, he goes on to imply that love is ridiculous, "the only one thing in the world more ridiculous than a merry Christmas." This affirms my prior statement that Scrooge does not value anything so much as he values money; while the rest of society tends to place a pretty high premium on love, Scrooge does not. To go to Fred's house to celebrate a holiday he thinks is stupid and wasteful with people who are "in love" would be perfectly odious to him.
Of course, Scrooge first utters his famous "Bah, humbug!" Then he asks his nephew, "What right have you to be merry? What reason have you to be merry? You're poor enough."
To this the nephew counters, "What right have you to be dismal? What reason do you have to be morose? You're rich enough." Scrooge retorts that he needs to be morose because he lives in a "world of fools." Scrooge continues,
If I could work my will...every idiot who goes about with 'Merry Christmas' on his lips, should be boiled with his own pudding, and buried with a stake of holly through his heart. He should!
The nephew is shocked by Scrooge's coldness, but Scrooge tells his nephew to keep Christmas in his own way, and he will keep Christmas in his.
To continue from the previous post, Scrooge tells his nephew to keep Christmas in his own way, and he will keep Christmas in his. To this his nephew replies, "But you don't keep it." Scrooge says, "Let me leave it alone then!" There is also some subtext in the novel suggesting the Scrooge is not particularly fond of the girl that his nephew chose to marry, although it does not appear that he has ever actually met her.