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)

824. He had a name written that no one knew but Himself. This symbolically means that what the Word is like in its spiritual and celestial senses, no one sees but the Lord, and the person to whom He reveals it.

A name symbolizes someone's character (no. 165 and elsewhere), here the character of the Word, or what the Word is like inwardly, that is, in its spiritual and celestial senses. It is said to be a name written, because the Word exists both among people on earth and among angels in heaven (see The Doctrine of the New Jerusalem Regarding the Sacred Scripture, nos. 70-75.). No one's knowing the name but Himself means, symbolically, that no one but the Lord Himself sees it, that is, what the Word is like in its spiritual sense, and the person to whom He reveals it.

That no one sees the Word's spiritual meaning but the Lord alone, that no one accordingly sees that meaning unless enabled to do so by the Lord, and that no one is enabled to do so by the Lord unless he possesses Divine truths from the Lord, may be seen in The Doctrine of the New Jerusalem Regarding the Sacred Scripture 26.