There are, the famous opening lines of the Didache state, “two paths: one of life and one of death, and the difference between the two is great.” These were some of the lines I was asked to translate when I entered seminary, and we were slotted into an Exegesis class on the basis of such testing. Jokes abound about “there are two kinds of…”. Jesus absorbed the same way of discerning humans, and he sees two sorts of humans: the few who enter the narrow gate and the many who enter the wide gate.

Probably no text is more directly offensive to the postmodern (or modern) pluralistic sensibility. One path, so Jesus states, leads to destruction; the other path leads to life. You can monkey with these words, but their implication is clear: a choice needs to be made to follow Jesus or not.
And let this be observed before we get to quick to announce that is we, and not the others, who have entered the narrow gate: the narrow gate is entered by those who hear the words of Jesus in the Sermon on the Mount and do them; the wide gate by those who hear those words and do not do them. So there, each of us, we need to hear that. This isn’t about a simple “I accepted Jesus at five and I’ve lived the devil’s life every since but I’m safe and secure.” There is no reason to talk of the gate or the narrow way without thinking of the Sermon on the Mount.
So what is the “gate”? For a long time I’ve taught that the gate is Jesus himself, or Jesus as he is known through his teachings. To enter that gate is to answer the summons to follow Jesus (you can see why I think the Sermon on the Mount is an evangelistic sermon).
A summary is in order: to enter the narrow gate involves being with the blessed ones (poor, peacemakers, persecuted, etc), being salt and light consistently, following Jesus’ radical way about murder/anger, adultery/lust, divorce, truth-telling, mercy over revenge, loving enemies. And it involves doing good deeds for the right reasons; it involves pursuing the kingdom and God’s justice instead of fortunes and fame; and it involves not damning the others and trusting that God is good.
That’s the narrow gate about which Jesus teaches.
What about numbers here? Is this a calculation of how many will make it and how many won’t? Maybe. It is more likely, as Allison and others have argued, that it is Semitic over-statement in a potent exhortation.
The point is clear: there are severe alternatives when we hear the words of Jesus. To do them or not to do them — and that makes all the difference.