Either the disciples are accustomed to calling down fire on folks or they’re blowing smoke. I’m voting for the latter. But then church folk do get a little hot under the collar when what they believe to be sacred is not well received. Jesus puts out their passion for revenge (and ours?) with a rebuke and the narrative continues with three on the road sayings. The cost of following Jesus will be high. No home. No time to bury the dead. No turning back. We tend to have an easier time of it and even if we make sacrifices we are not without the comforts of home or time to mourn or take care of business before doing whatever it is God has called us to do. So we are either “not fit for the kingdom of God” or the text does not apply to us. I’m going to opt for a middle way aka the Lutheran solution. We may indeed have comfortable places to lay our heads and take time to bury our dead and say farewell before following but being fit for the kingdom depends wholly on the One who had the power to call down fire on rude Samaritans but did not. So what might seem as an absolute (…not fit for the kingdom) is actually a rebuke and a rebuke is correction not rejection. And in the Lutheran solution the rebuke of the law always leads one to cling more firmly to the Gospel which is the only way we are ever fit for the kingdom of God.