Their search was not random, but it happened under the guidance of the Holy Spirit. Yet Peter deliberately calls him the Spirit “of Christ.” The point is that through the working of his Spirit, Christ Jesus was active in the old dispensation, prompting prophets to speak about himself. Psalm 22:1–31 and Isaiah 53:1–12 are very clear and obvious examples. Precisely because of the work Jesus did in the Old Testament dispensation (long before his incarnation!), Jesus could tell the Jews that the (Old Testament) Scriptures were all about him (John 5:39; Luke 24:27; see also Luke 4:21; Luke 22:37).
11 inquiring what person or time the Spirit of Christ in them was indicating when he predicted the sufferings of Christ and the subsequent glories.