Marriages on earth are the seedbed of the human race and also of the angels of heaven, for as already noted in its own chapter, heaven is from the human race. For this reason, and because they do have a spiritual origin (from the marriage of the good and the true), and because the Lord’s divine nature flows especially into this love, these earthly marriages are seen as most holy by heaven’s angels. Correspondingly, adultery, as the opposite of marriage love, is seen by them as unholy; for as angels see in marriages a marriage of the good and the true, which is heaven, so in adultery they see a marriage of the false and the evil, which is hell. So if they even hear adultery mentioned, they turn away. This is why heaven is closed to people if they commit adultery because they enjoy it. Once it is closed, the Divine Being is no longer acknowledged, nor is anything of the faith of the church.
I could tell that everyone in hell is opposed to marriage love from the aura that emanated from hell. It was like a ceaseless effort to break up and destroy marriages. This showed that the dominant pleasure in hell is the pleasure of adultery, and that the pleasure of adultery is also the pleasure of destroying the union of the good and the true, the union that makes heaven. It follows from this that the pleasure of adultery is a hellish pleasure, diametrically opposed to the pleasure of marriage, which is a heavenly pleasure.
There were some spirits who plagued me with particular ingenuity because of their practice during their physical life. They did this by a rather subtle inflow, almost wavelike, a kind that is characteristic of honest spirits; but I could tell that there were elements of deception and the like within them, intended to ensnare and deceive. Eventually I talked with one of them who had been in command of an army when he lived in the world, so I was told. Since I could tell that there was something licentious in what he was processing mentally, I talked with him about marriage in a spiritual language, using images—many of them very brief—that expressed my sentiments fully. He said that during his physical life he had thought nothing of acts of adultery.
It occurred to me to tell him, though, that acts of adultery are unspeakable, no matter how different and even permissible they may look to people like him because of the pleasure they are grasping and their consequent rationalizations. He might realize this simply because marriages are the seedbed of the human race and therefore the seedbed of the kingdom of heaven. Because of this, they should never be violated but should be regarded as holy. He might also realize this because he must know that he was now in the other life and in a state to perceive that marriage love was coming down from the Lord through heaven, and that mutual love, the foundation of heaven, was derived from that love as from a parent. There was also the fact that when adulterers merely approach heavenly communities they become aware of their own stench and dive down toward hell. He should at least know that violation of marriage is against divine laws and against the civil laws of all kingdoms as well as contrary to genuine rational light because, among many other things, it is contrary to both divine and human order.
However, he answered that he had not thought that way during his physical life. He wanted to quibble about whether this was true or not; but he was told that there is no quibbling about the truth. Quibbling favors whatever pleases us, and therefore supports what is evil and false. He should first think about what he had been told, because it was true. Or again, he could start from the principle widely acknowledged in the world that we should not do anything to others that we do not want them to do to us. So if anyone had practiced this kind of deception on his own wife, whom he loved (as is the case in the early stages of every marriage), then when he was at the peak of his blazing rage about it and gave voice to his feelings, wouldn’t he himself hold adultery to be detestable and, being intellectually gifted, wouldn’t he of all people defend his condemnation to the point of damning adultery to hell?
I have been shown how the pleasures of marriage love lead to heaven and how the pleasures of adultery lead to hell. The path of marriage love toward heaven led into constantly increasing blessings and delights until they were beyond number or description. The deeper they were, the more of them there were and the more indescribable they were, all the way to the delights of the inmost heaven, the heaven of innocence. All this was accomplished with the greatest freedom, because all freedom stems from love; so the greatest freedom comes from marriage love, which is the essential heavenly love.
On the other hand, the path of adultery led toward hell, step by step to the very lowest where there is nothing that is not grim and terrifying. This is the kind of fate that awaits adulterers after their life in the world. By “adulterers,” we mean people who find pleasure in acts of adultery and not in marriage.
from Heaven and Hell, Sections 384-386