These two descriptive words are placed side by side so that each might strengthen the other (grammatically known as a hendiadys). The two words, then, emphasize that these words
are definitely true. So John (and the churches to whom John must send this, Revelation 1:10) is duty-bound to embrace these words
and work with their content.
6 And he said to me, “These words are trustworthy and true. And the Lord, the God of the spirits of the prophets, has sent his angel to show his servants what must soon take place.”