Jamieson, Fausset and Brown on 1 Peter 1:19

19. precious--of inestimable value. The Greek order is, "With precious blood, as of a lamb without blemish (in itself) and without spot (contracted by contact with others), (even the blood) of Christ." Though very man, He remained pure in Himself ("without blemish"), and uninfected by any impression of sin from without ("without spot"), which would have unfitted Him for being our atoning Redeemer: so the passover lamb, and every sacrificial victim; so too, the Church, the Bride, by her union with Him. As Israel's redemption from Egypt required the blood of the paschal lamb, so our redemption from sin and the curse required the blood of Christ; "foreordained" (1Pe 1:20) from eternity, as the passover lamb was taken up on the tenth day of the month.