It’s slightly misleading to talk about it in that way in that it suggests that there’s a polemic purpose behind his fiction. He certainly has strong convictions and overt themes in his novels, but he’s not trying to write a tract or a treatise in order to try to change things.
The clearest example of that is in one of his greatest novels, ‘Little Dorrit’, which is centred on the Marshalsea debtors’ prison, which had closed 20 years previously. Patently the object is not to reform the debtors’ prison, but to deal with the themes that were important there. Having said that, it’s also true that when he wrote about the Poor Laws, he was trying to change attitudes toward those. When he wrote about the Yorkshire schools, within a few years many of the most notorious schools had closed down. So there are specific instances, but I'd stick to the main point I made which is that he's writing fiction that is designed to entertain and enlighten people.
"He's trying to enlighten and change our attitudes, particularly our attitudes towards other people because, at the end of the day, as George Orwell pointed out many years ago, Dickens' vision comes down to a platitude. Namely: Love your neighbour."
I think in some ways the classic instance of this side of his work is to look at 'Oliver Twist' which starts out with trenchant satire on the Poor Law system but at the end of the day his solution to it is a change of attitude because the image that is known by people who have never heard of Dickens is Oliver asking for more. What that does is to cut through all the arguments that were being made for years before and after the Poor Law about what the best way was to deal with poverty and people who need support, both worthy and unworthy people. What Dickens does is to reduce the whole issue down to a single word. Should an innocent child, without love, without support, have 'more'. And not just more gruel, but more love, more attention, more clothing and so on.
https://www.youtube.com/embed/nlJugdk4OGc?wmode=opaque
It's not a program he's trying to change things with, but what he is trying to do is explain to us that if we're really human, we have to be on the side of Oliver. He's trying to enlighten and change our attitudes, particularly our attitudes towards other people because, at the end of the day, as George Orwell pointed out many years ago, Dickens' vision comes down to a platitude. Namely: Love your neighbour.
He very much believes in New Testament Christianity and the specific thing that he believes in is to care for one's fellow human beings. The thing is to be kind to one another, to be thoughtful to one another, to see the other person's point of view, it's an important part of being human. The classic example of this is 'A Christmas Carol'. Scrooge is wrapped up entirely in himself and his business, and what he learns is that Tiny Tim needs attention and Bob Cratchit needs attention and he could have had a lovely wife is his views had been better – if he'd been a good man.