The Orientals, when walking fast, or working, found it convenient to gather up their long, flowing robes by means of a girdle. During the Millennium, it seems, the Lord will take part in the activities of his people. But righteousness and faithfulness, not militarism and hypocrisy, will be his strength, the force of his reign, his girdle.
Loins. Were supposed to be the seat of strength. To gird up the loins was, in prophetic parlance, to make ready for work, or for traveling untrammeled.
Reins. The same as kidneys. Supposed to be the symbols of desire; also of knowledge, joy, pleasure. Sometimes coupled with the heart. (Rev. 2:23)