Why not? Because there is no such thing as "earth spirits". All religion and spirituality is a lie and a crutch. There is no after-life, no god(s), and no "great veil" between "worlds".
Grow up. Do good work. Be kind to and love one another. Why bring imaginary bullshit into it?
We know about the stars and the why the sun rises, we don't have to shackle out mind to ignorant superstitions any longer.