I'll echo others: be careful with your assumption that an atheist world-view must be the worst. My experience also bears out that this is not what troubles even a highly sensitive child. Hanni has been okay for quite a long time with the idea that when we die, our bodies become part of the earth, and our minds just stop existing.
Instead, what upsets her is (for the past year) thoughts of violent death and violence between people, and (more recently) thoughts of her loved ones dying, and her desire that she and I die at the same time.
