Wouldn't you think that "fear" and "comfort" are antonyms, like "love" and "hate," or "darkness" and "light"?
Proverbs book, a chapter of 40+ pages traces the concept its older Old Testament appearances, just so we can begin to understand of Solomon's use throughout the book of Proverbs. One discovery is that the concept itself frames and must color our understanding of each individual verse within the entire book.
When we develop the concept Biblically, we feel the burden to show that the fear of Yahweh is not (as some might think) an Old Testament concept as opposed to a New Testament concept. Indeed, it is quite literally a pan-Biblical concept.
This stood out to me in a recent daily Bible reading. Acts 9:31 leapt out at me in this context:
Ἡ μὲν οὖν ἐκκλησία καθ᾽ ὅλης τῆς Ἰουδαίας καὶ Γαλιλαίας καὶ Σαμαρείας εἶχεν εἰρήνην οἰκοδομουμένη καὶ πορευομένη τῷ φόβῳ τοῦ κυρίου καὶ τῇ παρακλήσει τοῦ ἁγίου πνεύματος ἐπληθύνετο.There's that same phrase we find in the OT; in fact, the Septuagint of Proverbs 9:10 has φόβος κυρίου ("fear of the Lord), as the beginning of wisdom. The post-Pentecost Christian church proceeded in that same fear. They lived their life from that motivation, the very same motivation found throughout the OT, and identified by Solomon as the necessary starting-place of knowledge (1:7) and of wisdom (9:10).
So the church throughout all Judea and Galilee and Samaria had peace and was being built up. And walking in the fear of the Lord and in the comfort of the Holy Spirit, it multiplied.
That in itself is instructive and thought-provoking. Though they'd been saved by the shed blood of Christ, though the Spirit had been outpoured, though non-Jews were beginning to be brought in, yet one thing that united them all is that they moved on in their Christian lives with the motivation of fear of the Lord.
But then notice the next phrase: "and in the comfort of the Holy Spirit." Luke sees and depicts this quality as seamlessly joined with the preceding. The two are joined by a simple "and," not "and yet" or "and by contrast," nor qualified by "sometimes... sometimes."
Clearly, the jarring disconnect we feel between fear and comfort was not a problem to Luke. It was fear that gave the heart and mind the right stance before God; it was comfort given by the Spirit that assured and encouraged him in the life he was moved to live.
I conclude that either, to the exclusion of the other, is an unhealthy imbalance. Conversely each, coupled with the other, is a spiritually healthy blend.
What God has joined, we shouldn't sunder.