Your logic:

Atheists don't believe in a god --> They don't care about earth or anything
Theists believe in a god --> They care about stuff

These jumps do not follow logically. If I don't believe there's a god controlling day-to-day events on earth, couldn't I be MORE not less interested in understanding the world, how it works, and how to preserve it, rather than rely on a God and his will to just let things take their course. Conversely if you believe in a heaven and afterlife, couldn't you care LESS and not more about other topics beyond securing salvation?

You have it backasswards.