Revelation 14:17

17. And The misty forms of the white cloud, its occupant, and the harvest field, have all instantly disappeared. But a second and more terrible, though equally transient, volume of the sky-picture appears in its place to complete the series of omens. To the harvest of wrath succeeds the vintage of blood. By the phrase temple in heaven Dusterdieck and Alford are somewhat nonplussed. The word heaven means, as often elsewhere, the firmamental heaven, (note Revelation 4:11,) or sky. And the simple meaning is, that a visional temple, with its altar, outlined itself in the sky-vision as part of the omen scenery.

Angel… sharp sickle The Lord of the harvest has reaped the grain; but leaves to his servants the treading of the bloody winepress. The blood-red colour of the juice of the grape suggests the thought of carnage; and the pressure by which it is crushed out suggests the wrath that compels the carnage. The image is taken from Isaiah 63:3, where Jehovah’s treading the winepress and pouring forth the blood of the grape, is an image of the crushing of the wicked powers in behalf of his people.