1 Peter 1:11

εἰς τίνα ἢ ποῖον καιρὸν, searching (to discover) what or what manner of season was pointed to (εἰς). If God withheld from them the precise time when His promises were to be fulfilled, they desired at least to know whether it was to be in the immediate or only in the distant future.

πνεῦμα Χριστοῦ can hardly mean “the Spirit which spake of Christ,” taking Χριστοῦ as an objective genitive. Nor is it likely to mean merely the Spirit which in after days dwelt in Christ. It might mean the Spirit belonging to or proceeding from Christ Himself. Certainly the Holy Spirit is described as πνεῦμα Χριστοῦ, Romans 8:9; πνεῦμα Ἰ. Χ., Philippians 1:19; πνεῦμα Ἰησοῦ, Acts 16:7; πνεῦμα τοῦ υἱοῦ, Galatians 4:6. In John 1:9-10, the Logos is described as having been all along in the world; a light was coming into the world to lighten every man. So Justin Martyr, Apol. i. 36, describes the prophets as moved by the divine Logos and sometimes speaking in the person of Christ, ἀπὸ προσώπου τοῦ Χριστοῦ; and Clem. Al. adv. Haer. IV. 7. 2, says: Qui adventum Christi prophetaverunt revelationem acceperunt ab ipso Filio.

According to this interpretation Christ is described as inspiring the prophets by His Spirit to predict the sufferings destined for Himself.
But (see Hort, p. 52) we must remember that Χριστὸς, with or without the article, was not originally a proper name, but a title, “Messiah,” “the Lord’s Anointed,” and, although Jesus Christ was the Messiah, the nation, the kings, and the prophets were also the Lord’s anointed; cf. Psalms 105:15, “Touch not mine anointed (τῶν χριστῶν μου) and do my prophets no harm.” Similarly in language which our Lord afterwards applied to Himself the prophet in describing his own mission, Isaiah 61:1 ff., says, “The Spirit of the Lord is upon me because He anointed me” (ἔχρισέν με). In this sense the prophets shared in the Messiahship of their Divine Master, and the Spirit which spake by them was the Spirit of the Lord’s anointed, πνεῦμα Χριστοῦ.

ἐδήλου προμαρτυρόμενον should probably be coupled together. δηλοῦν does not necessarily mean “to make plain.” The prophets were only able to discover part of what was meant. The word is used of making a communication to a person (1 Corinthians 1:11; Colossians 1:8), or of signifying or implying something indirectly (Hebrews 9:8; Hebrews 12:27).

μαρτύρεσθαι means literally “to call to witness,” so “to protest” as in the presence of witnesses; cf. Galatians 5:3; Ephesians 4:17, μαρτύρομαι ἐν Κυρίῳ. So here the sense seems to be that the Spirit which spake by the prophets asseverated in God’s name, “Thus saith the Lord.”

τὰ εἰς Χριστὸν παθήματα does not merely mean “the sufferings of Christ,” cf. 1 Peter 5:1, but “sufferings destined for the Messiah,” cf. τῆς εἰς ὑμᾶς χάριτος just above; cf. εἰς ὑμᾶς, 1 Peter 1:4; or “pointing to” Christ, cf. Acts 2:25, Δαυεὶδ λέγει εἰς αὐτόν. The sufferings described by the Prophets (e.g. Psalms 22, and esp. Isaiah 53.) only received their fulfilment in Christ.

In one sense the sufferings of O.T. saints were unconsciously on Christ’s behalf, and as it were “passed on” to Him (cf. Moses bearing the reproach of Christ, Hebrews 11:26), just as Christians now “fill up what is lacking in the sufferings of Christ,” Colossians 1:24, but it may be doubted whether St Peter intended to include that thought.