Remember that chapters and verses aren't part of the original text. So even though we consider a new chapter this week, the context continues from chapter 11. Jesus has pronounced woes on those who have been hypocritical, and now begins a longer section of teaching that's recorded as 12:1-13:21 (which bookend the teaching with the concept of leaven/yeast).
Some notes on the text…
Notice again the size of the crowds. There are so many people flocking to Jesus, which is undoubtedly playing a factor in the increasing animosity the Pharisees are displaying towards Jesus.
Leaven/yeast works by "infecting" a larger batch of dough. It only takes a little to affect the whole batch. Hypocrisy is subtle like that. The word we know comes directly from Greek, and was used of those who wore masks in a play (aka actors). To act hypocritically is to have the outside not match the inside, to "put on a show". Jesus is even here beginning to expose the Jewish religious leaders' hypocrisy here and now (from 11:38 and following), and warns His disciples to be on guard themselves about it.
There is both Law and Gospel here: we rightly should fear God because the only harm anyone else can do is a temporary thing: killing the body. But God has authority over the eternal state of body and soul. So it is rightly only Him that we should be afraid of. But we don't have to be afraid of Him because we know He cares for us, and all who trust in Him have the promise of His mercy towards them.
One of the biggest questions some people have is, "have I committed the unforgivable sin?". The simple answer is, if you're worried that you have, you haven't. To blaspheme the Holy Spirit is to be offered the gifts of grace and mercy that God gives in Christ and to persistently, completely, and finally reject them in unbelief. Those who commit the unforgivable sin are those who reject forgiveness through to the end of their earthly lives.
This whole section addresses faith as well, but from a different angle: faith in what? The parable—as almost all parables are—is prompted by a question or situation around Jesus, and is used to answer this man in the crowd who was trying to get what he felt he was owed. The rich man in the parable trusted in himself alone - not even consulting with others to figure out what to do with his excess. His only thought was for himself. Faith in the gifts without recognizing the Giver is maybe the predominant problem of mis-placed faith in people: we have to have faith in something, and most often it's mis-placed by placing it in ourselves rather than God. And most often faith in ourselves manifests itself in greed.
12:32 Notice that it's God good pleasure to give the kingdom. God wants to give the gifts of the forgiveness of sins, salvation, and eternal life!
The theme of watchfulness is a common one in Jesus' teaching. I've often described this as "seeing with eternal eyes". Eyes that are completely and only focused on the here-and-now (and usually on ourselves in the here-and-now, from the above verses) will lose sight of the true blessing of eternal life, and therefore miss it when it comes.
In our culture that values "family first", these verses are hard to accept for a lot of people. How could Jesus bring division, when His mission is to bring reconciliaiton? We must understand the context. Earthly families are indeed a gift from God, but they are just that: earthly. There will be a time when earthly families are no more, and even during His earthly ministry, Jesus taught and demonstrated that (e.g. 8:19-21, 9:57-62, . Even within earthly families, there may be division because of Jesus; some within a family may follow Him and some may not.
Jesus returns to the theme of hypocrisy, but this time is addressing the crowds in general, not only the Pharisees and experts in the law. They can rightly interpret earthly things but are failing to rightly interpret the spiritual happenings of the time, namely that the kingdom of God is being brought to them right then and there in the person of Jesus. We would do well to heed all of these teachings of Jesus, including this one, which again reminds us that our eyes ought to be firmly fixed on Him in faith instead of on earthly things.