'Scarlet,' as in Genesis 38:28, signifies spiritual good.

In Isaiah 1:18, this signifies truth derived from good, or truth from a celestial origin, such as is the truth of the Word in its literal and natural sense

'Scarlet,' in Revelation 17:3, signifies truth from a heavenly origin, such as is the truth of the Word in the sense of the letter or natural sense, which is meant by what is holy in it. 

(Odkazy: Apocalypse Explained 67)

3486. The preliminary section of the previous chapter, paragraphs 3353-3356, explained what the Lord has said and foretold in Matthew 24:3-7 about the close of the age or end of the days of the Church. Here, in the Lord's Divine mercy, let the next section be explained, that is to say, verses 8-14 of the same chapter in that gospel, where it is said,

All these are the beginning of sorrows. At that time they will deliver you up to affliction, and will kill you, and you will be hated by all nations for My name's sake. And at that time many will stumble, and betray one another, and hate one another. And many false prophets will arise and will lead many astray. And because iniquity is multiplied the charity of many will grow cold. But he who endures to the end will be saved. And this gospel of the kingdom will be preached in the whole inhabited earth as a testimony to all nations; and at that point the end will come.