Who are the two witnesses and why is their appearance supernatural?
The two witnesses are not definitively identified in the passage; they could be Moses and Elijah. If so, their appearance is supernatural because two men who lived over 2,000 years ago would come back on the scene. This happens as the seven-year period begins, when the supernatural becomes commonplace.
Les explains that once the seven-year period starts—when the man signs the treaty with Israel and the Middle Eastern nations—the supernatural will become commonplace, unlike today when people are not used to angels intervening or God using an earthquake. He lists the appearance of the two witnesses as the first supernatural event, saying they will appear "whoever they are." If they are Moses and Elijah, it would be a supernatural phenomenon for two men who lived over 2,000 years ago to come back on the scene. He also connects this to the 144,000 Jews, 12,000 from each of the 12 tribes, whom God will supernaturally identify and send out, and to the escaping remnant of Jews fleeing Jerusalem to the mountains, who will be supernaturally escorted, just as Israel was supernaturally delivered from Egypt.