You bring up a good point when you say
"This world is a miraculous gift from God. Why aren't the churches leading the struggle to treat it that way?" Regardless of which party is in power, the evangelical right has the political clout to stop environmental depredations that are immoral, illegal, and tragic in their consequences to all.
and to be honest, many Christians are not as passionate about the planet as you may be. To them, although they are stewards of the environment, they do not venerate it or honor it as you do.
NIV writes:
Deut 4:15-20
15 You saw no form of any kind the day the LORD spoke to you at Horeb out of the fire. Therefore watch yourselves very carefully, 16 so that you do not become corrupt and make for yourselves an idol, an image of any shape, whether formed like a man or a woman, 17 or like any animal on earth or any bird that flies in the air, 18 or like any creature that moves along the ground or any fish in the waters below. 19 And when you look up to the sky and see the sun, the moon and the stars--all the heavenly array--
do not be enticed into bowing down to them and worshiping things the LORD your God has apportioned to all the nations under heaven.(from New International Version)
The planet is our home, to be sure. It is to be taken care of, to be sure. Many Christians, however, are not in the same frame of mind as many environmentalists, who, the argument goes, virtually worship nature.