Although at first it seems counterintuitive that a substitute would be acceptable, since one would think that man must atone for his own lack, it makes sense when we view the man as microcosm and everything on earth as an object over which he has dominion.
The materialist cannot see any distinction between human nature and the remaining hierarchy of animal natures, and may even deny much of a distinction between human life and vegetable life. For such a one, it is an injustice to imagine an ‘innocent creature’ such as a lamb, being slain as a ‘substitute’ for the human or for humanity as a collective whole. A bad anthropology destroys the concept of sacrifice.
Viewed in his proper role as the ‘microcosm’ summarizing in himself all of creation, surpassing all other forms of life by recapitulating them and transcending them, the religious man understands that he has power over all life and is to a degree free to make use of it according to his needs. It is not ‘unjust’ for man to use livestock for work and for food, because he is the master of that domain and there are no ‘animal rights’ that do not derive from the animal’s subordination to man. In other words, man has rights only in a relative sense, as derived from the rights of God and insofar as he is an image of God, and man’s rights are null and void before God’s, and man exists in total subordination to God’s purposes; likewise, animal (and vegetable) life only has rights insofar within the context of subordination to man and to his purposes and his goods. Animal rights derive from the purposes of man and from human nobility and from the role the animal plays in serving the good of man as the steward of God.
All that is to say that just as the life and death of man is ennobled only insofar as it is integrated into the divine work, whatever that may be, so also is animal life ennobled rather than degraded through its integration into the sacrificial economy. The fact of the martyr is the human manifestation of this ‘subordination unto death,’ although man, possessing free will and self-consciousness, submits to his participation by choice, and the animal victim only in a passive sense, since this is all that is possible.