A.T. Robertson Commentary 1 Peter 1:3

"Blessed [be] the God and Father of our Lord Jesus Christ, who according to his great mercy begat us again unto a living hope by the resurrection of Jesus Christ from the dead," — 1 Peter 1:3 (ASV)

Blessed be (ευλογητος). No copula in the Greek (εστω, let be, or εστιν, is, or ειη, may be). The verbal adjective (from ευλογεω) occurs in the N.T. only of God, as in the LXX (Luke 1:68). See also 2 Corinthians 1:3; Ephesians 1:3.

The God and Father of our Lord Jesus Christ (ο θεος κα πατηρ του κυριου ημων Ιησου Χριστου). This precise language in 2 Corinthians 1:3; Eph I:3; and part of it in 2 Corinthians 11:31; Romans 15:6. See Joh 20:17 for similar language by Jesus.

Great (πολυ). Much.

Begat us again (αναγεννησας ημας). First aorist active articular (ο, who) participle of αναγενναω, late, and rare word to beget again, in Aleph for Sirach (Prol. 20), in Philo, in Hermetic writings, in N.T. only here and verse 23. "It was probably borrowed by the New Paganism from Christianity" (Bigg). The Stoics used αναγεννησις for παλινγενεσια (Titus 3:5). If ανωθεν in Joh 3:3 be taken to mean "again," the same idea of regeneration is there, and if "from above" it is the new birth, anyhow.

Unto a living hope (εις ελπιδα ζωσαν). Peter is fond of the word "living" (present active participle of ζαω) as in 1:23; 2:4,5,24; 4:5,6. The Pharisees cherished the hope of the resurrection (Acts 23:6), but the resurrection of Jesus gave it proof and permanence (1 Corinthians 15:14,17). It is no longer a dead hope like dead faith (James 2:17,26). This revival of hope was wrought "by the resurrection of Jesus Christ" (δια αναστασεως). Hope rose up with Christ from the dead, though the disciples (Peter included) were slow at first to believe it.