Why did God choose a people at all?
It's the most basic question in biblical theology, and the answer determines what a congregation is for. If God chose a people for their own sake — to be his special possession, walled off from the world — then a closed, inward-facing church is faithful. If God chose a people for the sake of everyone else, then a closed church has inverted the reason it exists.
The Scriptures answer the question in the first sentence of election, and they never change the answer.
The purpose clause in the first promise
Next is the LORD had said unto Abram, Get thee out of thy country... And I'll make of thee a great nation, and I'll bless thee, and make thy name great; and thou shalt be a blessing... and in thee shall all families of the earth be blessed. (Genesis 12:1-3)
Read the grammar. Abraham is chosen. The sentence doesn't stop at his choosing. It has a purpose clause, and the purpose clause is everybody else: all families of the earth. The election of one man is stated, in its founding text, as the means of blessing all.
And it's repeated — to Abraham again (Genesis 18:18; 22:18), to Isaac (26:4), to Jacob (28:14) — with the same clause every time. The promise never appears without the nations attached to it. The first thing to know about the chosen people is that they were chosen for the unchosen.
A kingdom of priests
At Sinai, the nation receives its constitution:
Ye shall be unto me a kingdom of priests, and an holy nation. (Exodus 19:6)
Ask what a priest is for. A priest stands between God and people who aren't priests. A whole nation of priests only makes sense if there's a congregation they serve — and the congregation is the nations. Israel's constitution is priestly, and priesthood faces outward.
Then Moses tells them why the law-shaped life matters: this is your wisdom and your understanding in the sight of the nations, which shall hear all these statutes, and say, Surely this great nation is a wise and understanding people (Deuteronomy 4:6). The ordered common life exists to be observed by outsiders and to produce a conclusion in them.
The stranger in the temple's dedication prayer
When Solomon dedicates the temple, he prays for the foreigner:
Moreover concerning a stranger, that isn't of thy people Israel, but cometh out of a far country for thy name's sake... hear thou in heaven thy dwelling place, and do according to all that the stranger calleth to thee for: that all people of the earth may know thy name. (1 Kings 8:41-43)
The outsider is written into the temple's opening prayer. And the building had a court for him. Isaiah says why: mine house shall be called an house of prayer for all people (Isaiah 56:7).
Look at what Jesus was angry about when he cleared the temple. He quotes that verse: Is it not written, My house shall be called of all nations the house of prayer? but ye have made it a den of thieves (Mark 11:17). The court of the Gentiles — the outsider's space — was the space that had been turned into a market. The first thing to be commercialized was the room for the stranger.
"A light thing"
The prophets make the outward purpose explicit, even embarrassing:
It's a light thing that thou shouldest be my servant to raise up the tribes of Jacob, and to restore the preserved of Israel: I'll also give thee for a light to the Gentiles, that thou mayest be my salvation unto the end of the earth. (Isaiah 49:6)
A light thing. Restoring the chosen people is described as the smaller task. The nations are the larger one.
And Psalm 67 takes the priestly blessing itself — God be merciful unto us, and bless us; and cause his face to shine upon us — and attaches a purpose clause: that thy way may be known upon earth, thy saving health among all nations (Psalm 67:1-2). Bless us so that they will know. The blessing of the insider has the outsider as its object.
And the record writes the outsiders into the family where nobody could miss them: Rahab of Jericho and Ruth of Moab, in the line of David and of Christ (Matthew 1:5). Naaman the Syrian, healed (2 Kings 5). The widow of Zarephath, fed (1 Kings 17). Nineveh, spared (Jonah 3) — and a prophet sulking about it outside the walls.
Jesus says it first, and they try to kill him
In the synagogue at Nazareth, Jesus's first recorded sermon reminds the congregation that Elijah was sent to a widow in Sidon and not to any widow in Israel, and that Elisha healed a Syrian and not any leper in Israel (Luke 4:25-27). Outsiders. And all they in the synagogue... rose up, and thrust him out of the city, and led him unto the brow of the hill... that they might cast him down headlong (Luke 4:28-29).
That's how offensive the outward purpose of election is to insiders. It was the first thing he said in public, and it produced an attempted killing.
His parables keep the shape. Many shall come from the east and west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven (Matthew 8:11) — the outsider at the table. The great supper, where the invited refuse and the master says go out into the highways and hedges, and compel them to come in, that my house may be filled (Luke 14:23) — the purpose of the feast is a full house, filled with the uninvited. Other sheep I have, which are not of this fold: them also I must bring (John 10:16). And I, if I be lifted up from the earth, will draw all men unto me (John 12:32) — draw, a word for attraction.
And in his last prayer, the family's unity is given a purpose clause, and the purpose is the world: that they all may be one... that the world may believe (John 17:21). The oneness of the insiders is for the belief of the outsiders.
Paul: the promise to Abraham was the gospel
And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed. (Galatians 3:8)
Genesis 12:3 is the gospel, preached in advance. Paul doesn't treat the blessing of the nations as an implication of election. He says it's what the gospel is.
His account of the mechanism is attraction: through their fall salvation is come unto the Gentiles, for to provoke them to jealousy (Romans 11:11). The outsider is drawn by seeing what the insider has. And the outsider doesn't become a guest — he becomes household: ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God (Ephesians 2:19); if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise (Galatians 3:29).
Peter closes the circle by applying the Sinai constitution to a congregation of former outsiders:
But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light: which in time past weren't a people, but are now the people of God. (1 Peter 2:9-10)
Kingdom of priests, holy nation — now said of Gentiles. The outsiders have become the priestly people. And the purpose clause is there again: that ye should shew forth — display. Two verses later: your good works, which they shall behold (2:12).
A city with the gates left open
The end of the story is a city:
And the nations of them which are saved shall walk in the light of it: and the kings of the earth do bring their glory and honour into it. And the gates of it shall not be shut at all by day: for there shall be no night there. (Revelation 21:24-25)
The gates are never shut. The eternal city is permanently open to entrants — a great multitude, which no man could number, of all nations (Revelation 7:9). And the language for what God is doing across the whole arc is family language: bringing many sons unto glory (Hebrews 2:10); the firstborn among many brethren (Romans 8:29).
What this means for your congregation
God chose a people in order to grow a family. The chosen are chosen to be the visible, attractive, open household through which the family grows. Election is centripetal in its call and centrifugal in its purpose.
That's why there's a "third door" of apologetics at all — not because argument fails and we need something softer, but because the community was always the method: the thing outsiders were meant to see, be drawn to, and join.
So ask of your congregation: could an outsider find us? Could he see our common life from where he lives? Would there be a court for him — a space that hasn't been turned into a market? Is our unity aimed at the world's belief, or at our own comfort?
A congregation that's closed, homogeneous, inward-facing, and invisible to its neighbors hasn't merely failed at outreach. It has inverted the reason it was chosen. And the correction isn't a program. It is Genesis 12:3, read again, with the purpose clause restored.