Luke 9 and 10 contain a striking juxtaposition. In chapter 9 there is that famous incident where Jesus sent messengers ahead of Him into a Samaritan village, and Jesus was not received (9:53). The disciples wanted to call down fire from Heaven, just like Elijah, and torch the place. Jesus said that they did not know what spirit they were of (v. 55). And there, we think, the matter rests. We snuggle down into our new covenant cozies, glad that those days of wrath are over and done.
But just a few verses later, Jesus instructs his followers on what to do when they are not received in a town (Luke 10:10-12). They are to shake the dust off their garments, knowing full well that it will be more tolerable for Sodom than for that city. What happened to Sodom? Well, the same thing that the disciples had wanted to have happen to the Samaritan town in the previous chapter. And which Jesus rebuked them for.
And so clearly the rebuke was not for the thing they wanted to do, but rather for the way in which they wanted to do it. Their spirit was wrong. Jesus does not tell them that their spirit was wrong because they thought that the days of judgment were still with us. Their spirit was wrong because of the way in which they wanted that judgment to come. And so Jesus taught them the right way to invoke fire and brimstone from the sky.