After all sustainability means running the global environment - Earth Inc. - like a corporation: with depreciation amortization and maintenance accounts. In other words keeping the asset whole rather than undermining your natural capital.
In religious and in secular affairs the more fervent beliefs attract followers. If you are a moderate in any respect - if you're a moderate on abortion if you're a moderate on gun control or if you're a moderate in your religious faith - it doesn't evolve into a crusade where you're either right or wrong good or bad with us or against us.