What does Revelation 11:6 mean?
There has been much speculation about the identity of the two witnesses. The most popular choices are Elijah and Moses, but some Bible teachers suggest Enoch may be one of the two. They base this opinion on the fact that "it is appointed for man to die once" (Hebrews 9:27). Because Enoch did not die (Genesis 5:24), they believe he must die at a future time. Elijah also did not die, but was taken to heaven in a whirlwind (2 Kings 2:1–12).The identification of the two witnesses as Elijah and Moses is based on the witnesses' power to withhold rain from the earth, which Elijah did when he was a prophet in Israel (1 Kings 17:1; James 5:17), and to smite the earth with plagues, which Moses did when he told Pharaoh to release the Hebrews from bondage (Exodus 7:14—12:29). It was also Elijah and Moses who were present at Jesus' transfiguration (Matthew 17:1–8). Jewish tradition believed Moses and Elijah would return in the future (Deuteronomy 18:15, 18; Malachi 4:5), but these Old Testament references were also fulfilled by Jesus and John the Baptist. Another consideration is that Moses and Elijah are the human representatives of the Law and the Prophets, both of which bear witness to God.
Of course, the two witnesses could be entirely different people. In the final analysis, it is not necessary to know exactly who the two witnesses are. What matters, in this context, is what they do.
The witnesses' sackcloth demonstrates their mourning over Israel's backslidden condition. This is a common symbol, especially in the Old Testament, of regret and sadness (Genesis 37:34; 2 Samuel 3:31; Jonah 3:5).