Life is more valuable to an atheist

First, no disrespect to any religious people out there, and this is just my opinion, it doesn't apply to everyone.

Anyway, as an atheist, I value life a lot. I'm pro life, anti euthanasia, and I support life extension research. A big part of why I value life so much is because I don't think there's anything after we die. I think once we die, everything just goes dark and our consciousness ends. As someone who enjoys living and thinking, I would prefer to live for as long as possible, and I also want others to be able to experience life.

When I think about religion, and the belief of an afterlife, whether it's heaven/hell, reincarnation, ghosts, etc, I always think what's the point of grieving someone's passing if they don't really die, but instead continue existing in another form and another place? Especially in believe systems where you'll be able to see them again someday. This is something I'm genuinely curious about, why do religious people take death seriously if they believe people continue living after death?