So lets look at the questions I raised in the OP...
Turning water of rivers into blood is an environmental disaster of huge proportions.
Are we not told that He will make a new heavens and a new earth?
Is there a subtle idolatry when we change focus from Jesus and the great commission to looking after the earth?
Anything is idolatrous when it replaces the Lord.
I believe that good theology includes good theology about creation. And good theology about creation means recognizing the innate goodness of the creation. The earth is good, there is an innate goodness because God is the Author of creation and He declared all that He made "exceedingly good".
We also live in an age of death and disorder, creation suffers and is subjugated to the futility of death and decay, out of which God is going to rescue and redeem it. That is why we believe in the healing and redemption of creation: new heavens and new earth. But our future hope is never permitted to be an excuse for present evil. This is true of many things, such as justice. We believe, and hope, that in the end God's justice shall prevail and all shall be made right; because in this fallen world there is great injustice. But this present injustice, and our hope for future justice is never permitted as an excuse for us to be complacent--or worse, complicit--in present injustice. When God established His covenant with Israel He established His Law, He made Israel to be a nation of justice and order in an unjust and disordered world; a place where rather than more of the same injustice--the poor, the hungry, the needy being left out and suffering--Israel was to be a people who took care of the least of these, where there would be justice for widows, justice for victims, justice for the poor, the hungry, and the needy. Where those who committed injustice would be brought to justice, and there would be restitution.
Which is why Christians have always also upheld the necessity of a lawful, just, and peaceful (insofar as it is possible) society in which there can be human flourishing. We love our neighbor, not merely by abstaining from cruel acts toward them, but by actively seeking what is good for our neighbor, holding to the Rule of "Do unto others as you would have them do unto you." This has always been the essence of Christian ethics, to do what is right, and to seek the good not just for ourselves but for our neighbors, especially for the marginalized and the least of these.
In application to creation, broadly speaking, again Scripture speaks quite clearly against evil against God's creation. Cruelty toward animals is forbidden, sinful, and evil. The laws which governed Israel included laws for letting beasts of burden feed upon part of the field crop as well as setting aside part of the yield as a tithe for the Levites, foreigners, and the poor. "You shall not muzzle the ox" means exactly this.
The bounty of the earth is to be celebrated as God's gift, rather than treated as something to be exploited--the exploitation of God's good creation has often been a source of not just acts of cruelty toward creation, but cruelty toward our neighbors. When we go to war over resources, people suffer; when we seek to steal the land of others we make it so those others cannot enjoy the bounty of that land. When we poison our lakes and rivers we harm everything that depends on those lakes and streams--including ourselves, the towns and villages where people need clean drinking water, and depend on the health of the land to provide food, and labor.
Environmental concerns should never become an idol. But Christian ethics, and good theology, means that we understand that while in this present fallen age there is evil and injustice, we are supposed to act and live in ways which are counterfactual to the present way of things; we are not to be collaborators with death, but stand in defiance of death as advocates of life. The day is coming when every sword and spear is beaten into instruments of life rather than death, and where men will no longer remember the ways of war; but even today should be the day that we say we trust not in chariots or their horses, but in the Lord; today is the day that we say justice for our neighbor. We don't merely say "the wicked will face Judgment" and never do anything; we place barriers in the way of temporal evil with temporal judgments, not denying the future Judgment nor thinking our judgments replace God's; but we recognize that for the sake of good for us and our neighbors there needs to be an ordered society of rules. There needs to be some semblance of justice right now, even in the midst of this unjust world of death and decay. Where we promote life and the flourishing of life, rather than collaborate and become complicit with the wickedness of death. That applies to everything, from the microscopic level of our day-to-day interpersonal relationships, to the macroscopic level of human governance, the organization of society, and our relationship with non-human creation.
-CryptoLutheran
