From the perspective of religious ethics, animal welfare is of utmost importance because animals are part of God’s creation. This importance becomes obvious in the very beginning of the Torah. The first commandments given by the Lord to humans and animals concern the welfare and survival of animals and human stewardship responsibilities toward them. Similarly, the Bible emphasizes kindness to animals, which is required in the Ten Commandments.
In terms of cruelty to animals, Judaism has strict laws. An entire code of laws (“tsa’ar ba’alei hayim,” the requirement “to prevent the suffering of living creatures”) mandates that animals be treated with compassion. Christianity also forbids cruelty to animals since they are created by God. Two disciples quote Jesus as saying that God loves even the “lowliest” of creatures. In Islam, any cruelty toward an animal is considered a sin.
According to Jewish tradition, animals are capable of developing spiritually. Jews believe that someone who neglects animals cannot be good in God's eyes.
This belief is also seen in Buddhism. Buddhists try to do as little harm as possible to animals, avoid any jobs connected with the killing of animals, and respect animals and humans equally. In Buddhism, both humans and non-human animals are capable of reaching Nirvana, the highest state of well-being.
To apply these religious teachings to animal testing, using animals for research purposes becomes unethical. Inflicting any harm on animals regardless of the purpose is intolerable.