Talking about Christ dying on the cross for all of life, not just human beings, they thought was rather radical. There are, however, several other religious and spiritual traditions which do promote exactly this sort of awareness to varying degrees, and they tend to be rooted in eastern and aboriginal cultures. If western religious traditions promoted an anthropocentric view of the universe, then at the opposite end of the spectrum are those that cultivate a more pantheistic perspective. Life is a constant flux and humans should put themselves in harmony with it. Buddhists likewise look for harmony.
All life is one and indivisible.
The overriding moral value is compassion for all beings. Neither Taoists nor Buddhists find it necessary to invoke God as a creator or a manipulator of his creation. Hindus have many gods but associate them with a nature vibrating with life. Such life allows animals, including humans, to move in and out of each other through reincarnation. Once individuals adopt the belief that God and the universe are one and the same, it isn't hard to understand how these religious convictions can translate to green politics.