'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)

3222. In addition to this, loves and the affections belonging to them are represented by means of flames, which are indescribably varied. Truths however are represented by means of lights and by means of countless modifications of light. From this it may be seen how it comes about that flames in the Word mean goods that are the goods of love, and lights truths that are the truths of faith.