The loins, as in Ezekiel 29:7, signify the marriage of truth and good. In general, loins signify love, and when referring to the Lord, divine love. They can also signify the interiors of conjugial love. In Isaiah 11:5, they signify people in the divine good of love, and reins signify people in love towards their neighbor.

(References: Apocalypse Revealed 830)

831. 19:17 Then I saw an angel standing in the sun; and he cried with a loud voice, saying to all the birds that fly in the midst of heaven, "Come and gather together for the supper of the great God." This symbolizes the Lord, out of Divine love and so out of Divine zeal, calling all people who have a spiritual affection for truth and think about heaven, and summoning them to the New Church and to conjunction with Himself, thus to eternal life.

The angel standing in the sun means the Lord in His Divine love. The angel means the Lord, and the sun His Divine love. Crying with a loud voice means, symbolically, out of Divine zeal, for a voice or influx coming from the Lord out of Divine love is an expression of Divine zeal, inasmuch as zeal is a characteristic of love. Birds that fly in the midst of heaven symbolize all people who have a spiritual affection for truth and so think about heaven. To come and gather together for the supper of the great God symbolizes a calling and summoning to the New Church and to conjunction with the Lord; and because conjunction with the Lord is attended by eternal life, therefore this, too, is symbolically meant. To cry "come" symbolizes a calling, and "gather together" symbolizes a summoning.

[2] That an angel in the Word means the Lord may be seen in nos. 5, 170, 258, 344, 465, 649, 657, 718 above, and the more so here because he was seen standing in the sun, and no angel appears in the sun. For the Lord is the sun in the spiritual world, and therefore the Lord alone is present in it. That the sun in reference to the Lord symbolizes Divine love may be seen in nos. 53 and 414. Clearly, to cry with a loud voice in reference to the Lord in His Divine love means, symbolically, to speak or flow in out of Divine zeal; for Divine zeal is a characteristic of Divine love, in this case for the salvation of humankind. That birds symbolize such things as are connected with the intellect and consequent thought may be seen in no. 757 above, and in this case people who have a spiritual affection for truth and think about heaven, since the cry is addressed to birds that fly in the midst of heaven, and to fly in the midst of heaven means, symbolically, to discern, focus on, and think (nos. 245, 415). That the supper of the great God symbolizes the New Church and thus conjunction with the Lord, may be seen in no. 816, where that supper is called the marriage supper of the Lamb.