@aidan,
The very fact that Christians believe that their life is a key to another world, the “afterlife”, shows that they don’t think that this life is of the utmost significance.
This world is just a means to an end, which is the next life, the “afterlife”. Of course, Christians believe that this life is important, but they do so only in terms of getting to heaven, and not because they believe it’s the only life they can be sure they have.
Atheists value this life because this life is the only one they can be sure they have, and that very idea, that we each have only one life to live and try and do something significant, gives life that much more meaning and beauty, a kind of transient and fleeting beauty, whereas the emphasis for Christians in this life is on making sure you do what’s right in order to get to the afterlife.
That is the highest pursuit in a Christian’s life, is it not? What else could be more important for a Christian than making God happy by doing what he tells you to do, and doing what necessary to get to heaven?
Surely, in a Christian worldview, the planet can become overwhelmed by global warming, but so long as you adhere to God’s law, then that doesn’t matter.
That’s the point someone else was trying to make, that what happens in this world is of no consequence, providing that you the Christian, abide God’s law, which is the most important thing in a Christian world.