John Calvin Commentary Numbers 19:2

"This is the statute of the law which Jehovah hath commanded, saying, Speak unto the children of Israel, that they bring thee a red heifer without spot, wherein is no blemish, [and] upon which never came yoke." — Numbers 19:2 (ASV)

This is the ordinance of the law. Because it was inevitable that, while the faithful were engaged in the world, they would often contract some pollution through contact with its many impurities, the composition of the water is described here, by the sprinkling of which they could wash away and expiate their uncleanness. Then, certain kinds of pollution are specified for which purification is required.

God commands that a red heifer be slain, one that had never been subjected to the yoke. It was to be burned outside the camp, along with its skin and dung. The ashes were to be gathered by a clean man and stored outside the camp for the common use of the people. However, so that the water mixed with these ashes would have the power of reconciliation, God simultaneously commands that the priest sprinkle the blood seven times before the altar with his finger.

This ceremony had a twofold purpose. First, God wanted to awaken the people’s attention to reflect more closely on their impurity. Even if they were pure inwardly, He wanted them to look around carefully, lest they be polluted from external sources. Second, He also taught them that whenever they contracted any pollution, expiation was to be sought from an external source, namely, from sacrifice and sprinkling. Thus, He admonished them that people search in vain within themselves for the remedies required for their purification, because purity can only come from the sanctuary.

Those who speculate with subtlety on the details propose some questionable ideas. Therefore, I leave them to enjoy their own fanciful notions. It is enough for us to consider generally what God intended by this ceremony and what benefit the people received from it.

Some suppose that the red color signifies sin. Meanwhile, to avoid an obvious contradiction, they are forced to interpret absurdly what follows—that God required a perfect heifer without blemish—as if it meant there should be no variation in the color of her hair. In contrast, God demands the same thing as in other sacrifices, which were rejected as flawed if any mark of deformity was present in them. It is in this sense that it is added that she should never have borne a yoke. Therefore, I have no doubt that God commanded that a pure heifer, neither mutilated nor lame, should be chosen, and, so that her perfection might be more apparent, one not yet broken to the yoke.

What, then, is the meaning of the red color? First of all, I prefer to confess my ignorance rather than to propose anything doubtful. However, it may be conjectured that a common and ordinary color was chosen instead, so that it would not be too noticeable, as it would have been if it were either white or black. But this should be considered certain: a perfect heifer, free from every blemish, was to be offered—one, too, that had not been broken to the yoke by human hands, so that the purification might have nothing of human effort in it.

The command to offer her was given to all the people because, for us to be partakers of this cleansing, it is necessary that each of us offer Christ to the Father. For although He alone, and that only once, offered Himself, still a daily offering of Him, accomplished through faith and prayers, is commanded of us. This is not such an offering as ²² the Papists have invented, by whom, in their impiety and perversity, the Lord’s Supper has been wrongly turned into a sacrifice because they imagined that Christ must be slain daily so that His death might benefit us. However, the offering of faith and prayers, of which I speak, is very different, and by it alone we apply to ourselves the power and fruit of Christ’s death.

²² See the dogmatical statement of this notion in the Creed of Pius iv.