Discussion on Strait and Narrow

Yes, it is understood that the narrow path is considered to be a metaphor for the entrance into the kingdom of heaven, which only occurs to those who are born again. Many are called, but few are chosen.  Once Jesus has got you, you are in. But even so, consider Paul's admonition to Christians at Corinth whom he called babies. They were still on spiritual baby food, and not consuming adult spiritual fare. These Christians were not making much progress spiritually. Get a move on! Paul was saying.

1 Corinthians 3:1-3

1. And I, brothers, was unable to speak to you as I would to spiritual people, but spoke to you as flesh-driven people – babies in Christ.
2. I have fed you baby food, not food for adults, because you couldn't handle it. And you still can't handle it,
3. because you are still flesh-driven. That is, doesn't the envying, strife and divisiveness among you show that you are flesh-driven, no different from non-spiritual people?

Here we should observe that Paul need not have worried overmuch, as Jesus himself said that persecution would afflict (and discipline) his real followers.

The "old man" (another Paulism) within the true Christian was hanging back, avoiding the narrow path.  It seems quite probable that some of the early congregants were not believers, but people who had joined for social reasons. Those congregants would have had a tendency to hold back the others, cajoling them to just hang about and "play church."

Recall the married couple Ananias and Sapphira who had the misfortune of lying to the Holy Spirit (Acts 5:1-10). No doubt they knew no better because they did not know Jesus.

Surely an example of someone who took the narrow path was Paul.  Paul gave up all comforts and went all out to serve God and bring in an enormous harvest of souls for Jesus.

2 Corinthians 11:24-28

24 Under Jewish rulers, I have received the maximum of 39 stripes [more than that required Roman approval].
25 On three occasions I was beaten with rods, another time I was stoned and three times I was shipwrecked, spending a night and a day in the ocean.
26 In my many travels, I have been in peril of waters, in peril of robbers, in peril from my own countrymen, in peril by the pagans, in peril in the city, in peril in the wilderness, in peril at sea, in peril from false Christians.
27 Tired and hurting, often on the lookout, hungry and thirsty, often fasting, cold and badly clothed.
28 Aside from all those sort of things that befall me every day, I also have concern for all the church groups.

Yet, with all that, Paul is hardly the only fiercely determined Christian in the annals of faith. Many are the unsung heroes who have endured all manner of troubles as they labored in the fields of the Lord. They have forgone everything and have done and are doing amazing things under Jesus' authority – even though many such works are hidden for now.

You might think of such Christians as the elite special forces for the Lord. But they are people who in fact, not only in word, have surrendered all. Those Christians who have yet to find this very narrow path will, I suspect, still be walking a path off the big highway, where all the world walks. That is to say, even a reluctant Christian must show himself different from ordinary worldlings. The Spirit within him will at least nudge him "go this way, duck that." The Spirit within him will lead him, by degrees perhaps, to take a narrower way. The Christ within him will master the darkness of the old man, though the old man, abetted by Satan, puts up a ferocious struggle. If necessary, God can even drag the troubled believer into the wondrous New World.