Sure. Green symbolizes life. If atheists are devoid of God then devoid of life, then they wouldn’t reflect light and be entirely devoid of color, like vampires.
This means, the moment you are atheist, mirrors no longer reflect your image because you’re no longer there.
But here. Have some chlorophyll cells. They convert sunlight to life energy via magnesium and life-magic. You’ll be fine.
Of course it’s possible that you’re not a sunlight creature in which case perhaps atheists use chemosynthesis, in which case atheists are sulfur-based life forms, aka Christian hell