The 'city of Judah,' as in Isaiah 40:9, signifies the doctrine of love towards the Lord and love towards our neighbor.

(Referenser: Apocalypse Explained 850)

209. For thou hast some power, and hast kept My word, and hast not denied My name, signifies that they have power from the Lord against evils and falsities, in the measure in which they make truths from the Word to be of the life, and acknowledge the Divine of the Lord in His Human. This is evident from the signification of "having power," as being power from the Lord against evils and falsities; and as those who are in faith from charity are treated of, it is said that they "have some power" (of which presently). It is evident also from the signification of "to keep My word," as being to make truths from the Word to be of the life; for to keep truths or commandments means not only to know and perceive them but also to will and do them, that is to keep them; and those who will and do, make the truths that they know and perceive from the Word to be of their life (See also above n. 15). It is evident also from the signification of "not denying My name," as being to acknowledge the Divine of the Lord in His Human (See above, n. 135).

[2] It should be known that there are two principal things of the church, namely, the acknowledgment of the Lord's Divine in His Human, and making the truths from the Word to be of one's life; moreover, no one can be in the one of these unless he is at the same time in the other; for all truths that are made to be of the life are from the Lord, and this is done with those who acknowledge the Divine in His Human. For the Lord flows in with all, as well in the heavens as on the earth, from His Divine Human, and not from the Divine separately. Consequently those who in their thought separate the Divine of the Lord from His Human, and look to the Divine of the Father not as in the Human but as beside it or above it, thus separated from it, receive no influx from the Lord nor thus from heaven, for all who are in the heavens acknowledge the Lord's Divine Human (See concerning this in the work on Heaven and Hell 2-12, 59-72, 78-86. From this it is clear that all truths that are made of the life are from the Lord with those who acknowledge the Divine in His Human, that is the Divine Human. Truths become of the life when man loves them, thus when he wills them and does them, for he who loves, wills and does; in a word, truths are made of the life when man from affection lives according to them. Such truths are from the Lord because the Lord flows into the love with man, and through the love into truths and thus makes them to be of the life.

[3] Something shall now be said about the power that man has from the Lord against evils and falsities. All power that angels have and also that men have is from the Lord; and the measure in which they receive the Lord is the measure of their power. He who believes that any power against evils and falsities comes from what is man's own [proprium] is greatly mistaken; for it is evil spirits, conjoined to the hells, that induce evils and falsities thence with men, and these spirits are numerous, and each one of them is conjoined to many hells, in each of which also there are many spirits, and no one except the Lord can turn these away from man, for the Lord alone has power over the hells, and man has no power at all from himself or from what is his own [proprium]; therefore man has power to the extent that he is conjoined to the Lord by love. There are two loves that reign in the heavens and constitute the heavens, namely, love to the Lord and love towards the neighbor; love to the Lord is called celestial love, and love toward the neighbor is called spiritual love. Those who are in celestial love have much power, but those who are in spiritual love have some power; and because what is written to the angel of this church, treats of those who are in love towards the neighbor, or in charity and in faith therefrom, which love is spiritual love, it is said, "Thou hast some power."

[4] But it is to be noted, that all the power that angels and men have from the Lord is from the good of love; and since the good of love does not act from itself but through truths, therefore all power is from the good of love through truths, and with those who are spiritual, from the good of charity through the truths of faith. For good takes on a quality through truths, good without truths having no quality and where there is no quality there is neither force nor power. From this it is clear, that good has all power through truths, or charity through faith, and neither charity apart from faith nor faith apart from charity has any power. This is meant also by the keys given to Peter, for "Peter" there means, in the spiritual sense, truth from good which is from the Lord, thus faith from charity; and the "keys" given to him the power over evil and falsities. These things were said to Peter when he acknowledged the Divine of the Lord in His Human; which means, that those have power who acknowledge the Divine of the Lord in His Human, and from Him are in the good of charity, and in the truths of faith. That these things were said to Peter when he acknowledged the Lord is shown in Matthew:

Jesus said to the disciples, Who say ye that I am? Simon Peter answered and said, Thou art the Christ, the Son of the living God. And Jesus answering said unto him, Blessed art thou Simon Bar-Jonah; for flesh and blood hath not revealed this unto thee, but My Father who is in the heavens. But I also say unto thee, thou art Peter, and upon this rock I will build My church; and the gates of the hells shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven (Matthew 16:15-19).

(But of Peter and his keys, see what is said above, n. 9; also what is shown in The small work on The Last Judgment 57, and in The Doctrine of the New Jerusalem 122; and that truth has all power from good, which is from the Lord, in the work on Heaven and Hell 228-233, 539, and Arcana Coelestia 3091, 3387, 3563, 4592, 4933, 6344, 6423, 7518, 7673, 8281, 8304, 9133, 9327, 9410, 10019, 10182).