Judean syntax (Jude 1:20-21)

Here's one for you:

ὑμεῖς δέ ἀγαπητοί ἐποικοδομοῦντες ἑαυτοὺς τῇ ἁγιωτάτῃ ὑμῶν πίστει ἐν πνεύματι ἁγίῳ προσευχόμενοι 21 ἑαυτοὺς ἐν ἀγάπῃ θεοῦ τηρήσατε προσδεχόμενοι τὸ ἔλεος τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ εἰς ζωὴν αἰώνιον

I mean to update and pretty up this post later, when I have access to my tools. But here's the deal:

1. You see that Jude has one finite verb (specifically one imperative), surrounded by three participles.
2. Me, I dismiss out of hand renderings that reduce all the participles to imperatives.
3. So what we have is one finite verb anchoring three participles. I've been surprised, though, not to find more syntactical comment on the relationship of the whole.
4. The dominant idea is keep yourselves in the love of God.
5. I take it that the first two participles indicate means: "by building yourselves up and praying"
   
6. If you accept that, is the third also modal? If not, what?

Refinements, disagreements, discussion?

Have at it.