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)

3773. 'And they would put the stone back in its place over the mouth of the well' means that it was closed up for the time being. This is clear from what has been stated about the stone over the mouth of the well, in 3769, 3771. With regard to these considerations, namely that the Word was uncovered for the Churches and after that closed up, the position is that in the beginning, when any Church is established, the Word is in that initial period closed up to them but later on, through the Lord's provision, is opened up. And from there people learn that all doctrine is based on these two commandments, that the Lord is to be loved above everything else, and the neighbour as themselves. When these two commandments are the end in view the Word is in that case opened up, for all the Law and all the Prophets, that is, the whole of the Word, hangs on them, as does everything from them, and so everything has reference to them. And being in that case governed by the primary teachings concerning truth and good people receive light in each particular thing they see in the Word. For the Lord is present with them at that time by means of angels and is teaching them even though they are not directly aware of it, and is also guiding them into the life of truth and good.

[2] This may also be seen from the consideration that in their infancy all Churches have been such, and have from love worshipped the Lord, and have from the heart loved the neighbour. But in course of time Churches have moved away from these two commandments, and have turned away from good flowing from love and charity towards those things called matters of faith, and so have turned away from life towards doctrine. And to the extent this happens the Word is closed up. These are the factors meant in the internal sense by the words, 'Behold, a well in the field, and behold, three droves of a flock there, lying nearby it; for out of that well they watered the droves; and there was a large stone over the mouth of the well. And all the droves would be gathered there; and they would roll the stone from over the mouth of the well and water the flock; and they would put the stone back in its place over the mouth of the well'.

104. Verse 4. But I have against thee that thou hast left thy first charity, signifies that they do not make such a life as those lived who were in the church at its beginning, the essential of knowledges. This is evident from the signification of "first charity," as being a life according to the knowledges of good and truth, such as those lived who were in the church at its beginning (of which presently); and from the signification of "leaving that charity," as being not to make it the essential of knowledges; for those who are eager for the knowledges of truth and good, and who believe that they are saved thereby, make knowledges essential, and not life, when yet a life according to knowledges is the essential. But as this essential of the church and of salvation is treated of in what follows, more will there be said about it. Charity is life, because all life in accordance with the precepts of the Lord in the Word is called "charity;" therefore to exercise charity is to live according to those precepts. (That this is so, see in The Doctrine of the New Jerusalem, in the chapter on Love to the Neighbor or Charity 84-106; and in the small work on The Last Judgment 33-39.) The life of the church at its beginning is here meant by "first charity;" for every church begins from charity, and successively turns away from it to faith alone or to meritorious works. (On which subject, and on charity, see what is shown in the Arcana Coelestia, namely, that every church begins from charity, but in process of time turns away from it, n. 494, 501, 1327, 3773, 4689; thus to falsities from evil, and at length to evils, n. 1834, 1835, 2910, 4683, 4689; commonly to faith alone, n. 1834, 1835, 2231, 4683, 8094. A comparison of the church in its beginning and in its decline, with the rising and setting of the sun, n. 1837; and with the infancy and old age of man, n. Arcana Coelestia 10134; that the church is not with man until the knowledges of good and truth have been implanted in the life, n. 3310; that charity constitutes the church, n. 809, 916, 1798, 1799, 1844, 1894; that the internal of the church is charity, n. 4766, 5826; that there would be one church, and not many, as at this day, if all were regarded from charity, although they might differ in respect to doctrinals of faith and rituals of worship, n. 1286, 1316, 1798, 1799, 1834, 1844, 2385, 2982, 3267, 3451; that worship of the Lord consists in a life of charity, n. 8254, 8256; that the quality of worship is according to the quality of charity, n. 2190.)