Selection from Apocalypse Explained ~ Emanuel Swedenborg
Heaven with man is implanted by means of the knowledges of truth and good from the Word. He who believes that heaven is implanted by other means is much deceived; for man is born merely natural, with the faculty of becoming spiritual, and he becomes spiritual by means of truths from the Word and a life according to them. Who can ever become spiritual unless he has some knowledge of the Lord, of heaven, of the life after death, of faith, and of love, and of the other things that are means of salvation? If man had no knowledge of these things he would remain natural; and a merely natural man can have nothing in common with the angels of heaven, who are spiritual. Man has two minds, one exterior, the other interior. The exterior mind is called the natural mind, but the interior is called the spiritual mind. The former or natural mind is opened by means of the knowledges of the things that are in the world; but the latter or spiritual mind by means of the knowledges of the things that are in heaven, which the Word teaches, and the church from the Word; by means of these man becomes spiritual when he knows them and lives according to them.
This is meant by the Lord's words in John:
Except a man has been born of water and of the Spirit, he cannot enter into the kingdom of God (John 3:5)."Water" signifies the truths of faith, and "spirit" a life according to them.
Most people at this day believe that they are to come into heaven solely by virtue of holy worship in temples and by adorations and prayers, but such of them, as do not care for the knowledges of truth and good from the Word, and who fail to imbue with these the life, as well as the memory, remain natural as before, and do not become spiritual - for their holy worship, adorations, and prayers, do not proceed from any spiritual origin, since their spiritual mind has not been opened by the knowledges of spiritual things and a life according to them, but is empty.
Worship that proceeds from what is empty is merely natural gesture, with nothing spiritual in it. If such persons are insincere and unjust in respect to moral and civil life, their holy worship, adorations, and prayers have within them what repels heaven from them, instead of opening heaven to them as they believe - for their holy worship is like a vessel containing things putrid and filthy, which are oozing forth, or like a splendid garment investing a body covered with ulcers. I have seen many thousands of such cast into hell.
But wholly different are holy worship, adorations, and prayers with those who are in the knowledges of truth and good and in a life according to them; with such these acts are pleasing to the Lord, for they are the effects wrought by their spirit in the body, or the effects of their faith and love, thus they are not merely natural gestures, but spiritual acts.
From this it can be seen that the knowledges of truth and good from the Word, and a life according to them, alone make man spiritual; and that in him who is thereby made spiritual, angelic wisdom from the Lord can be implanted together with eternal happiness. Angels derive happiness from no other source than from wisdom.
(from Apocalypse Explained 126)