iano:
According to traditional Christianity (or at least it does not clash with traditional Christianity) an animal is just a mechanical (in a biological sense) thing and to talk of cruelty to mechanical things is down to skewed thinking.[...]
Wow.
Is this your belief?
This sort of belief is common, and might actually be part of traditional western thought. I have come across atheist philosophers with a similar view of animals as mechanical robots with no consciousness. Such beliefs are more common on the political right, with some on the political left going to the opposite extreme.
Historically, it wasn't just animals. Members of primitive tribes were treated as sub-human. As recently as 50 years ago, many conservative Christians in the U.S.A were treating blacks as subhuman.
Even today we see Bush, with support from conservative christians, demonizing some people as terrorists, in order to justify torturing them. Never mind that they might actually be innocent.
Compassionate conservatism - bringing you a kinder, gentler torture chamber