Human beings are by nature deeply self-centered. I think this is very close to what the Bible means by saying we are born sinful -- not that we are born as axe murderers, but that we are born selfish. People say, "How can you look at a beautiful, innocent baby and say we're born sinful?" But a baby is the most selfish creature in the world -- it has no sense of where it stops and others start, and everyone and everything exists simply to meet the baby's wants and needs. That's selfish.
We read the Bible selfishly. We read a passage and the first question we usually ask -- even responsible, Christ centered followers of Jesus -- is, "How does this apply to me?" That's a self-focused way of reading the Bible, and it gets us into trouble.
So in this particular passage, we more often than not read these verses and we think Jesus is talking about the end of the world, or at the very least about how I can get to heaven. "What does it mean for me to enter through the narrow door?" Well, that means that I have to be a genuine follower of Jesus to get to heaven, and not just go along with the world's wide ways. Right?
Why don't we read instead with the goal of understanding what Jesus originally meant? What situations was he speaking to, and who heard him? How did his disciples originally understand his words, and why did Luke, in this case, choose to record them? Why were these words important to Luke? This kind of reading is harder, because we have to get outside our own point of view and become students of the history and context of the Bible.
How does this contextual study help us understand a passage like this one? To start with, it's no accident that verses 31-35 are included on the heels of verses 21-30, though we usually separate them. Jesus is approaching Jerusalem, and he has a deep sense of the impending danger facing this beloved city. Jesus ascribes this danger to the Jews' rejection of God's prophets throughout history, and now specifically to their rejection of him as Messiah. So many of Jesus' parables and teachings focus on exactly this topic. (See for one example Matthew 21:33-41.) Jesus sees the overwhelming tide in his own culture, a kind of Jewish nationalism that idealized the Maccabean revolt a century and a half before, reread the prophet Daniel breathlessly because they believed it foretold a Messiah arriving any day (just a little irony there) and hated the Romans and Herod and the Jewish high priests who collaborated with these powers. In context, Jesus seems to be saying, If you allow yourself to continue thinking like this, you will be destroyed. That spirit of rebellious nationalism is the wide road that everyone around you assumes is correct. I have come to show you a different way.
In fact, that tide of nationalism did erupt in a rebellion against Rome in 66 AD, and Rome responded with an iron fist. After a siege lasting years, Jerusalem was destroyed. Jesus' followers, however, saw what was coming and withdrew to the town of Pella in Syria, largely because they remembered Jesus' teachings calling them away from that kind of nationalistic fervor and armed conflict.
So is it possible that Jesus' immediate context in speaking these words, and Luke's in recording them, is looking ahead a couple decades to the sack of Jerusalem and the destruction of the temple? Scholars debate at length whether Luke's gospel was written before or after 70 AD when the temple was destroyed, and that really doesn't matter a lot. Anyone with eyes to see in the decades leading up to the Jewish War of 66-70 AD could tell what was going to happen. And is Jesus also, in this context, warning the Jews that the movement he starts will move beyond a strictly Jewish one and become open to people of all different tribes and nations? That seems to be the thrust of verses 28-30. This idea -- that the Jews would be disgraced (as they had been in 586 BC when Nebuchadnezzar sacked Jerusalem) and that other nations would be welcomed into the kingdom of God in their place -- would have been horrifying to the Jews of Jesus' day, and would indeed have been grounds for weeping and gnashing of teeth. We don't need to leap to medieval visions of Dante's Inferno to interpret Jesus' words.
What then, to do with the secondary question of how to apply these words to ourselves? If you can't see that an unbridled nationalism is dangerous, you haven't been paying attention to the news. And if you don't realize that Jesus offers a different, narrower door than the triumphalism of "we're claiming this nation back for God" that so much Christianity trumpets, you need to reread the Bible, starting with the gospels.
It is hard work to read the Bible this way, but it is a more honest way of coming at the text. All it really is, is good listening: Understand the speaker and what they mean, get the message clear in that context, and only then interpret it for your own situation. Good communicators do this every day. We need to learn to do this as we read Jesus' words as well.