"Make every effort to enter through the narrow door, because many, I tell you, will try to enter and will not be able to. Once the owner of the house gets up and closes the door, you will stand outside knocking and pleading, 'Sir, open the door for us.' "But he will answer, 'I don't know you or where you come from.' Then you will say, 'We ate and drank with you, and you taught in our streets.'But he will reply, 'I don't know you or where you come from. Away from me, all you evildoers!' There will be weeping there, and gnashing of teeth, when you see Abraham, Isaac and Jacob and all the prophets in the kingdom of God, but you yourselves thrown out. People will come from east and west and north and south, and will take their places at the feast in the kingdom of God. Indeed there are those who are last who will be first, and first who will be last." (Luke 13: 24-30)

Jesus is answering a question:
Someone asked him, "Lord, are only a few people going to be saved?" (Luke 13:23)
Jesus answers by using metaphors to explain what ecclesiastical translators are mistakenly translating as being a physical location - the "kingdom of God."

As explained with Luke 13:18-19 and Luke 13:20-21, the word being translated to "kingdom" is βασιλεία (basileia). This means, "royal power, kingship, dominion, rule - 1) not to be confused with an actual kingdom but rather the right or authority to rule over a kingdom."

Rather, Jesus is speaking of accepting God's dominion or authority over our personal lives. Jesus is speaking of taking shelter in the Supreme Being and devoting ourselves to Him.

So what is the "narrow door"? The Greek word στενός (stenos) being translated to "narrow" also means "strait." A "strait" is understood to be a narrow shipping channel or waterway.

Just consider a strait for a moment. A ship that sails through a strait must maintain a very diligent course - with great care and good navigation. This is also the manner in which we need to steer our lives towards the Supreme Being: With the utmost of care and respect.

Why? Because the Supreme Being is not an object. He is not a monolith or a white light or an impersonal force. Rather, the Supreme Being is a person - with a personality. He is a person who like any person, has likes and dislikes.

Just consider if a boy wanted to become the boyfriend of a girl he barely knows. What will he do? If he is smart, he will find out what she likes and then do that to please her. If he finds she likes flowers, he will bring her some flowers. If he finds that she likes baseball cards, he'll give her some baseball cards. Whatever it is, if he wants to find a way into her heart, he will find out how to give her something that will please her.

The Supreme Being is also a person with likes and dislikes, and if we want to get close to Him - if we want to return to our loving relationship with Him - then we will strive to come to know Him, and do things that please Him.

One of the main facilities for pleasing the Supreme Being is to follow the guidance of one who is already engaged in a loving relationship with God - one who is already pleasing the Supreme Being. The Supreme Being engages in loving relationships because He enjoys love. He enjoys being loved and He enjoys loving. He enjoys the exchange of a loving relationship.

The central means into such a loving relationship is established by participating in a relationship with one who already participates in a relationship with God. His representative.

Jesus is offering this to his students because he is involved in such a loving relationship with God. He is God's representative. This is confirmed by such statements as:
"I seek not to please myself but Him who sent me." (John 5:30)
"For I have come down from heaven not to do my will but to do the will of Him who sent me." (John 6:38)
So what does the analogy of the owner of the house mean?

The house is the loving relationship between the Supreme Being and His loving servant. The owner of the house is ultimately the Supreme Being - but because the house (loving relationship with God) is mutually shared with God's representative, His representative answers the door, and states:
"I don't know you or where you come from."
This type of "knowing" comes from the Greek word - which means to "understand, perceive" but also "to have regard for one, cherish" according to the lexicon.

In other words, it relates to having a relationship. "Knowing" someone in this context means sharing and exchanging love. Caring about each other.

If the one who shares a relationship with God says, "I don't know you - get away" - this means there is no common bond. They do not have a mutually-shared relationship.

This is communicated in another statement by Jesus:
"Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven. Many will say to me on that day, 'Lord, Lord, did we not prophesy in your name and in your name drive out demons and in your name perform many miracles?' Then I will tell them plainly, 'I never knew you. Away from me, you evildoers!'" (Matt. 7:21-23)
We can see with this statement that the criteria Jesus has for "knowing" a person - or sharing a common bond - is "only the one who does the will of my Father who is in heaven."

Thus we find the "narrow door" - the gateway into re-establishing our loving relationship with the Supreme Being: Doing the "will of my Father." In other words, doing what is pleasing to the Supreme Being.

This is the facility to return us to the relationship we were created to exchange with the Supreme Being. This is the process for having God and His representative open the door for us.

And what does that door lead to? Being "saved."

Being "saved" isn't about self-centered salvation. It means to return to our innate loving relationship with the Supreme Being. This is the "feast in the kingdom of God" Jesus is speaking of. [Though a better translation might be "feast of devotion to God."] This is the position of the prophets as Jesus mentioned - they are also exchanging loving relationships with God in the spiritual realm.

For a person who might have exchanged some conversation with Jesus - or in modern terms, just goes to church and does a bunch of rituals - and does not seek to love and serve the Supreme Being, Jesus states:
"Then you will say, 'We ate and drank with you, and you taught in our streets.' "But he will reply, 'I don't know you or where you come from. Away from me, all you evildoers!'"
Jesus established elsewhere that he was the door or gateway for a person to re-establish their devotion and loving service relationship with God:
"I am the gate; whoever enters through me will be saved. They will come in and go out, and find pasture." (John 10:9)
Once again, the "pasture" is re-establishing our loving service relationship with the Supreme Being.

This is a very practical matter. One might compare this to being introduced by a friend to someone important. Say if we want to know the President of the U.S., the best way is to become friends with a friend of the President. Then the friend will introduce us. But it is not as though we will "use" our friend. We must become true friends first.

Being introduced by an intimate friend is the process the Supreme Being engages for allowing us to return to our loving service relationship with Him. Each of us in the physical world rejected our loving relationship with Him - and were forced to take on a temporary physical body in the physical world. This physical body allows us to escape our relationship with God but it is also a place of rehabilitation.

This is the purpose of the "weeping" and "gnashing of teeth" - which are experienced by us who have taken on a temporary physical body and chase the illusory material energy - the various things of the material world.

These temporary sufferings are simply consequences for our own actions. It is not as though God is out for revenge. He simply set up a world of consequences in order to help facilitate our return to normalcy - which is what any loving parent would do for their children. If the child throws food, the child will need to pick it up. If he steals candy, he will need to make restitution or go to jail. This enables learning - and hopefully returning to our natural state of loving others and caring for others.

This rehabilitation is communicated with Jesus' statement:
"Indeed there are those who are last who will be first, and first who will be last."
This is called humility. A person who considers themselves to be less spiritually advanced will have better access to God because of their lack of pride. Those who are proud of their supposed advancement will be last because they think of themselves as first - superior.

When one becomes devoted to God's representative and God, that person automatically puts themselves last. They consider themselves unworthy. And such an attitude is attractive to the Supreme Being. This is the "narrow door." This is the access into a return to our loving service relationship with the Supreme Being.

Jesus confirms this in his "first and greatest" instruction:
‘Love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind’” (Luke 10:27)