There is a question as to whether Hebrews 1:8 should be translated, “Your throne, O God,” or as the RSV margin has it, “God is your throne”. The difficulty lies in the use of the nominative, “ho theos” (woodenly translated, “the god” — knowing that the article functions quite differently in Greek than in English). I think the standard translation is best, as I have written about this before. But here is yet another example of the nominative Ho Theos being used for the vocative. In the Psalms of Solomon, Psalm 2 we read verse in verse 15:
15 Ἐγὼ δικαιώσω σε, ὁ θεός, ἐν εὐθύτητι καρδίας, ὅτι ἐν τοῖς κρίμασίν σου ἡ δικαιοσύνη σου, ὁ θεός.Psalms of Solomon 2:15 (LXX)
Which the LES translates as:
16 I will justify you, God, in uprightness of heart, because your righteousness is in your judgments, God. Psalms of Solomon 2:16 (LES)
Ryle & James likewise translate the nominative as the vocative; as does R.H. Charles. Neither thought the translation even deserved a comment in their commentary on this Psalm. Indeed, the nominative being in apposition to the vocative “se” (you) makes it impossible to think how a nominative translation could be possible.
While this does not “prove” the translation in Hebrews 1:8, it does remove the silly objection that the nominative cannot be vocative, particularly when it comes to God. Thus, the real objection here is not with the grammar but with one’s theology. Those who reject a high early Christology do so on some other ground than merely grammar.