Another promise to this congregation was, "I also will keep thee from the hour of temptation, which shall come upon all the world." Some dreadful calamity is here predicted, during which the power of God would be mercifully manifested in granting this church a special preservation. Some suppose it to have reference to a great general persecution throughout the Roman empire, during which the Christians of Philadelphia would be spared. This may have been the fact; but whether it was or not, we have no means of information. When we come to consider the symbols of chapter 9, in which the delusive error of Mohammedanism is set forth, we will see what a period of sore trial this delusion was to the Eastern churches. It is also a fact that, in the midst of this abounding heresy, the church of Philadelphia was preserved as was no other church of Asia. When the followers of Mohammed were sweeping like a whirlwind over the Eastern empire, ravaging everything before them, Philadelphia remained an independent Christian city, when _all the other_ cities of Asia Minor were under the power of the Saracen sword. It held out against the Ottoman power until the year 1390 A.D., when it surrendered to Sultan Bayazid's mixed army of Ottoman Turks and Byzantine Christians (?). This was six years after the death of Wickliffe, "the morning star of the reformation," who opposed the corruptions of the Papacy, gave the world the first English translation of the Bible, and sowed the seeds that soon grew and produced a Huss, a Jerome, and a Luther. So God preserved the Christians of Philadelphia in the East until he began raising up others to herald his truth in the West, whose labors soon ripened into the glorious Reformation of the Sixteenth Century.