After this I looked, and I saw in heaven the temple—that is, the tabernacle of the covenant law—and it was opened. 6 Out of the temple came the seven angels with the seven plagues. They were dressed in clean, shining linen and wore golden sashes around their chests. (Revelation 15:5-6 NIV)
The judgments that God will cause to fall on unbelievers during the tribulation are truly horrible. They will contain terrors that are beyond compare.
And yet, these judgments are also Holy. God would not be a Holy God if He did not judge sin. So it is good and right for Him to punish those who remain committed to evil, even after being told to repent. God’s judgments, in this passage, are illustrated as coming straight out of the temple in heaven. These last “seven plagues” are carried by seven angels that each are dressed in “clean, shining linen” with “golden sashes around their chests.” The clean linen suggests that these angels are pure, completely without sin. They are not in anyway contaminated by the plagues that they are carrying. After all, they are simply performing acts of Holiness by judging the ones who refuse to repent. There is nothing wrong or sinful when the proper authorities judge sin with the appropriate measures.