The concept of a "church" in the Writings is both complex and beautifully organic, linked with teachings on the nature of the Lord and the resulting nature of mankind.

The Writings say that the Lord, in His essence - His actual substance - is perfect, infinite love, a love that powered creation, that is the ultimate source of reality, and that sustains reality constantly. That love is expressed in form as perfect, infinite wisdom, which gave form to creation and gives form to reality.

Deep stuff! You can read more about that elsewhere, but what matters here is that all of creation, from the smallest elements to the whole of the universe, reflects that same structure. It's present in nature itself, powered by the heat (love) and light (wisdom) of the sun. It's present in the essential forms of life, with plants (which are rooted; which change little; which are unfeeling; which are powered by light) representing elements of wisdom and animals (warm, feeling, mobile, ever-changing, powered by heat) representing forms of love. It's present in the near-universal division into male (wisdom) and female (love) aspects of plants and animals alike.

That structure is also in each of us. In common language we might call these our hearts and our minds - what we want and what we think. The Writings commonly talk of them as good (love; what we want in our hearts) and truth (wisdom; what we know in our minds) or as will (heart) and understanding (mind). Not only do these elements define us, they are also key to our spiritual fates. We can use them to accept the Lord's love, come into the good of life and ultimately go to heaven. We can also use them to reject the Lord's love and trot off to hell.

And there are further layers. The Writings say that all human societies are in human form, with functions analogous to the human body. This is true from small groups like families to large companies to entire nations and ultimately to both the entire human race in this world and the entirety of heaven in the next.

Among the most important human societies are, naturally, churches. Since the concept of a "church" is based on the human form, though, churches as referred to in the Writings can take many forms. At one end of the scale, any one person who has true ideas of right and wrong and lives by them is a church himself or herself. At the other end of the scale, all those in the whole world who believe in love of the neighbor – and act from that belief – collectively make up one church.

Many other varieties lie between those two extremes, but most references to "church" in the Writings mean the community of those who have the Word, know the Lord, and follow His commandments. These people have access to the best possible truth and deepest possible understanding about the nature of the Lord and what He wants from us.

Such a church plays a vital role: The Lord works through it to get ideas about being good into people's minds and the desire to be good into the inner recesses of their hearts, reaching far beyond that church itself to touch everyone in the world. In fact, the Writings say there is in essence a marriage between the Lord and the church, with the church in the role of the bride and wife, producing true ideas and good desires the way a wife produces children.

To protect this function, the Lord has made sure that throughout history (and a good bit of prehistory) there has always been a church filling this role.

The first of these was the Most Ancient Church, represented by Adam; it was inspired by love of the Lord. The second was the Ancient Church, represented by Noah; it was inspired by love of the neighbor and knowledge of the Lord. The third was the Israelitish Church, which had no interior love of good but preserved ideas of the Lord. The fourth was the primitive Christian church, which had a new, more direct understanding based on the Lord's teachings. The fifth, according to the Writings, is to be based on the deeper understanding offered through the Writings and their explanations of the Bible.

There is much more that could be said, but we'll just emphasize one other point:

We as individuals are who we are based on what we love, not what we know. We will go to heaven or to hell based on what we love, not what we know. Knowing, thinking and seeking truth are important things, but their purpose is to shape, guide and serve our loves; love is ultimately what matters. The Writings make it abundantly and repeatedly clear that it is the same with churches: They are ultimately based on love, not knowledge, on their determination to serve the neighbor, not their external forms of worship. And if churches share that common purpose of serving the neighbor then they are in essence one, with doctrinal variations being of little consequence.

(References: Apocalypse Revealed 533; Arcana Coelestia 407, 768, 1799 [3-4], 2048, 2853 [2-3], 2910, 2982, 3310, 3773, 3963 [2], 4292, 4672, 4723, 5826 [2-3], 6637, 6648, 8152, 9256 [4-5], 9276 [2]; Conjugial Love 116; Heaven and Hell 57; The Word 8; The Doctrine of the New Jerusalem Regarding the Sacred Scripture 99, 104)

57. We can say the same of the church as we have of heaven, since the church is the Lord's heaven on earth. It also has many components, and yet each is called a church and is a church to the extent that the qualities of love and faith rule within it. In it, the Lord forms a single whole out of the varied elements, and therefore makes a single church out of many churches. ¹

Much the same can be said of the individual member of the church as has been said about the church in general, namely that the church is within and not outside, and that anyone is a church in whom the Lord is present in the qualities of love and faith. ²

Much the same can be said of the individual who has the church within as has been said about the angel who has heaven within, that such an individual is a church in least form as the angel is a heaven in least form. Even more, we can say that the individual who has the church within is a heaven just as much as an angel is, for we have been created to enter heaven and become angels. So anyone who has the quality of goodness from the Lord is an angel-person. ³

It is worth noting what we have in common with angels and what we possess that they lack. We have in common with angels the fact that our deeper levels are formed in the image of heaven and that we also become images of heaven to the extent that we participate in the qualities of love and faith. What we have that angels lack is that our more outward levels are formed in the image of this world; and that to the extent that we are engaged in what is good, the world within us is subordinated to heaven and serves it; ⁴ and that then the Lord is present with us on both levels as he is in his heaven. He is actually present on both levels in his divine order, for God is order. ⁵

Footnotes:

7950. 'Even to the firstborn of the prisoner who was in the dungeon' means falsified truths of faith that occupy the last place of all. This is clear from the meaning of 'the firstborn in the land of Egypt' as faith separated from charity, as just above in 7948, and so also falsified truth of faith, dealt with below; and from the meaning of 'the prisoner who is in the dungeon' as those who occupy the last place of all, for his firstborn is placed at the opposite end of the scale from 'Pharaoh's firstborn who was to sit on his throne', which means falsified truth of faith that occupies the first place, 7779, 7949. 'The prisoner who is in the dungeon' is used to mean in the spiritual sense closest to the actual words one who thinks only on the level of his physical senses, and so is in utterly thick darkness so far as matters of truth and good are concerned; for he does not even possess the ability to perceive, as those who think on a more internal level of the senses do. This is the reason why those who occupy the last place of all are meant.

[2] The reason why 'the firstborn in the land of Egypt' means falsified truth of faith is that 'the firstborn of Egypt' is faith separated from charity, 7948; and those with this kind of faith are in nothing but complete and utter darkness so far as truths of faith are concerned. They cannot be in any light, and so cannot at all perceive what truth is or whether something is true. This is because all spiritual light comes from the Lord through good, that is, through charity. For the good of charity is like a flame from which light radiates, since good comes of love, and love is spiritual fire, the source of enlightenment. Anyone who imagines that people leading an evil life can also receive enlightenment in the truths of faith is very much mistaken. Their state may be such that they are able to produce proofs, that is, they may be able to prove the teachings of their Church, sometimes with skill and ingenuity; yet they are not able to see whether the things they prove are true or not. The fact that even falsity can be proved so adroitly that it seems to be the truth, and that a person is wise not when he can prove that something is right but when he can see whether it is, see 4741, 5033, 6865, 7011, 7680.

[3] Therefore a person whose life is sunk in evil is steeped in falsity arising from his evil; and no matter how well he knows what is true he does not believe it. Sometimes he thinks he does, but he is mistaken. He will be allowed to know in the next life that he does not believe it, when his perceiving is made to conform to his desiring. When that is done he will disown the truth, oppose it, and spurn it, and will acknowledge its opposite - falsity - as the truth. This now explains why those who are governed by faith separated from charity cannot help falsifying the truths of faith.