The metaphor of an idol suggests that Scrooge worships money which is not agreeable to Belle who feels as though Scrooge's lust for money has taken over. Money is almost like a false god to Scrooge. This is the language of commerce which demonstrates that Belle realises that Scrooge is obsessed with money. This is a biblical illusion to the gold calf which was worshipped
I have seen your nobler aspirations fall off one by one, until the master-passion, Gain, engrosses you.
Scrooge had far better ambitions for himself but gaining wealth has become his main goal. He is never going to change as it 'engrosses' him
You are changed. When it was made you were another man.
Belle does not recognise the man she first fell in love with. The direct address is not only towards Scrooge in the past but also the Scrooge looking at his past memories to show him what money did to him
That which promised happiness when we were one in heart is fraught with misery now that we are two
Belle feels as though Scrooge and her have separated from being the same person. In Christianity, the idea was that when two people get married they become one person but Belle feels that she and Scrooge have grown to be different
Dowerless girl
Belle affirms that she is not able to give him dowry which she believes is another reason for why Scrooge has lost affection for her.
But now a knocking on the door was heard...a man laden with Christmas toys and presents
Belle has grown up and has a husband and children. She leads a comfortable lifestyle which is not stained by one person wanting to obtain more wealth. Scrooge looking at this scene would feel extreme remorse as she had moved on but he never got into a relationship since