With a loud voice (which speaks of urgency and authority), this angel instructs the one who had the sharp sickle to get on with the harvest. His Sender has determined that the time has come for the cries of saints for justice and vengeance to be answered.
18 And another angel came out from the altar, the angel who has authority over the fire, and he called with a loud voice to the one who had the sharp sickle, “Put in your sickle and gather the clusters from the vine of the earth, for its grapes are ripe.”