John Calvin Commentary 1 Peter 1:19

"but with precious blood, as of a lamb without spot, [even the blood] of Christ:" — 1 Peter 1:19 (ASV)

As of a lamb—by this likeness, he means that we have in Christ whatever had been foreshadowed by the ancient sacrifices, though he especially alludes to the Paschal lamb.

But let us learn from this what benefit the reading of the Law brings us in this respect. For, though the rite of sacrificing is abolished, it still greatly assists our faith to compare the reality with the type, so that we may seek in the reality what the type contains.

Moses ordered a whole or perfect lamb, without blemish, to be chosen for the Passover. The same thing is often repeated regarding the sacrifices, as in Leviticus 23, Numbers 28, and in other places.

Peter, by applying this to Christ, teaches us that he was a suitable victim and approved by God, for he was perfect, without any blemish. If he had any defect in him, he could not have been rightly offered to God, nor could he pacify His wrath.