"[Narration] Old Marley was as dead as a door-nail. Mind! I don't mean to say that I know, of my own knowledge, what there is particularly dead about a door-nail. I might have been inclined, myself, to regard a coffin-nail as the deadest piece of ironmongery in the trade. But the wisdom of our ancestors is in the simile; and my unhallowed hands shall not disturb it, or the Country's done for. You will therefore permit me to repeat, emphatically, that Marley was as dead as a door-nail."
Simple: Old Marley was very dead. I do not know why the phrase "dead as a door-nail" is used; because a coffin-nail is a piece of metal used with dead people, that would make more sense to me. But that is not the phrase that people use, so I will leave it alone. Let me repeat: Old Marley was very dead.
"Merry Christmas! What right have you to be merry? What reason have you to be merry? You're poor enough." "Come, then," returned the nephew gaily. "What right have you to be dismal? What reason have you to be morose? You're rich enough."
Simple: "Why are you happy about Christmas? You have no money." The nephew says "why are you so sad and mean? You are rich."
"If I could work my will," said Scrooge indignantly, "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!"
Simple: "I wish that every fool that says 'Merry Christmas' was killed by his own boiling Christmas pudding, and then buried with a Christmas decoration buried in his heart.
"There are some upon this earth of yours," returned the Spirit, "who lay claim to know us, and who do their deeds of passion, pride, ill-will, hatred, envy, bigotry, and selfishness in our name, who are as strange to us and all our kith and kin, as if they had never lived."
Simple: "Some people say that they feel the Christmas spirit, but still do bad things. Christmas spirits do not know these people, as if they were never born."