New Defender's Study Bible Notes
3:7 Philadelphia. Philadelphia means “brotherly love,” and was named by King Attalus of Pergamum, its founder, in honor of his brother. Philadelphia still survives as the modern town Alasehir, located about twenty-eight miles southeast of Sardis.
3:7 no man openeth. The Lord here claims to have “the key of David,” referring to Isaiah 22:22: “And the key of the house of David will I lay upon his shoulder; so he shall open, and none shall shut; and he shall shut, and none shall open.” In Isaiah’s context, this promise was made to Eliakim, a servant of King Hezekiah. The “key” was the key to the national treasury, and figuratively to control of the government. Eliakim thus was a type of the Messiah, and Christ here asserts in effect that He controls the governmental economy of the whole world and all that happens therein.
3:8 little strength. Literally, “a little strength” simply reads “little strength,” since the article is not present in the Greek. The Lord’s promise of a continuing open door, therefore, is conditioned on the premise that the church (or any Christian ministry, for that matter) have little strength of its own, and thus relies wholly on the strength of the Lord. Worldly marketing methods may seem to yield large numerical results for a time, but will also produce gradual spiritual compromise and eventual disintegration.
In addition to the “little strength” criterion, of course, the church or other ministry must keep (that is “guard”) the absolute integrity of God’s Word, and uphold the name of the Lord Jesus Christ in all its sovereign power.