This response to Dan Wallace's comments on Hebrews 6 will be more technical than my previous comments in this series. I apologize for this up front, for it necessarily entails technical elements of Greek grammar.
Daniel Wallace offers his comments on Hebrews 6 within his Greek Grammar Beyond the Basis: An Exegetical Syntax of the New Testament (Grand Rapids: Zondervan, 1996), on page 633. There, he appeals to Sproule's essay when discusses the fifth participle in Hebrews 6:6, "fallen away" (παραπεσόντας) as doubtful that it should be taken as a conditional participle. Wallace reasons,
Heb 6:4–6 ἀδύνατον τοὺς ἅπαξ φωτισθέντας (6) καὶ παραπεσόντας, πάλιν ἀνακαινίζειν εἰς μετάνοιαν
it is impossible to restore again to repentance those who have once been enlightened (6) if they have fallen away
παραπεσόντας is often construed as conditional (a tradition found in the KJV and repeated in most modern translations and by many commentators). But this is unwarranted. The construction of vv 4–6 approximates a Granville Sharp plural construction (the only difference being that with the second participle in the construction, γευσαμένους in v 4, the conjunction τε is used instead of καὶ: τοὺς φωτισθέντας γευσαμένους τε καὶ μετόχους γενηθέντας καὶ γευσαμένους καὶ παραπεσόντας). If this participle should be taken adverbially, then should we not take the preceding two or three participles the same way? The inconsistency has little basis. Instead, παραπεσόντας should be taken as adjectival, thus making a further and essential qualification of the entire group. A better translation, then, is “It is impossible to restore again to repentance those who have once been enlightened . . . and have fallen away.”
All that I have said in response to Sproule and to Compton applies here, because like Compton, Wallace depends upon Sproule's brief essay to ground his claim that it is doubtfull that the fifth participle, "fallen away" (παραπεσόντας), should be taken as a conditional participle (hence, an adverbial participle).
Wallace adds to this claim the notion that "The construction of vv 4–6 approximates a Granville Sharp plural construction (the only difference being that with the second participle in the construction, γευσαμένους in v 4, the conjunction τε is used instead of καὶ: τοὺς φωτισθέντας γευσαμένους τε καὶ μετόχους γενηθέντας καὶ γευσαμένους καὶ παραπεσόντας)." What would it mean, if the construction conformed to the Granville Sharp rule? Wallace quotes Sharp,
When the copulative καὶ connects two nouns of the same case, [viz. nouns (either substantive or adjective, or participles) of personal description, respecting office, dignity, affinity, or connexion, and attributes, properties, or qualities, good or ill], if the article ὁ, or any of its cases, precedes the first of the said nouns or participles, and is not repeated before the second noun or participle, the latter always relates to the same person that is expressed or described by the first noun or participle: i.e. it denotes a farther description of the first-named person . . . .
Given Wallace's more thorough research and writing concerning the Granville Sharp rule, I wonder if he would not eliminate his suggestion that Hebrews 6:4-6 approximates the Granville Sharp rule.
Even if one were to take all five participles in Hebrews 6:4-6 as substantival (adjectival), the fact that they are plurals poses problems. Also, reflect upon the construction that strings together five participles on the following conjunctions underlined.
ἀδύνατον γὰρ τοὺς ἅπαξ φωτισθέντας γευσαμένους τε τῆς δωρεᾶς τῆς ἐπουρανίου καὶ μετόχους γενηθέντας πνεύματος ἁγίου καὶ καλὸν γευσαμένους θεοῦ ῥῆμα δυνάμεις τεμέλλοντος αἰῶνος καὶ παραπεσόντας πάλιν ἀνακαινίζειν εἰς μετάνοιαν ἀνασταυροῦντας ἑαυτοῖς τὸν υἱὸν τοῦ θεοῦ καὶ παραδειγματίζοντας
That this conforms to the Granville Sharp rule is doubtful at best. It is a stretch to appeal to the Granville Sharp rule to support the claim that Hebrews 6:4-6 entails five substantival participles. As I have been contending, this is dubious. More to come.