Why are believers still afraid of death?

[Der/die AtheistIn]

I think that change is difficult and often emotional.  You may find a similar reaction to a loved one who is moving away, and that you likely won't see them again or for a long while.  I've seen mothers cry when their child goes off to school for the first time, or then when moving out for college.  It's still a loss in the immediate sense.  So I wouldn't equate crying with fear.

As you had mentioned, Christians do have something to fear in the judgment.  There is also hope here.  But it seems to me, that your question can also be flipped around.   Apart from the emotional toll of change and an immediate loss.   Why do atheist cry at funerals?  If life is meaningless and there is nothing afterwords, then what does the non-believer have to fear (apart from the change and immediate loss I already mentioned)?

Also, I feel obliged to note, that I don't think that Christianity is about following the rules or checking off more boxes in one column over another.  There's only one box that needs to be checked (Are you His?)

Atheist don't neceserally think life is meaningless just because there is no God. Nihilism is the philosophy that there is no objective meaning to the world, but it doesn't mean there isn't any subjective, many atheists are nihilists. Because atheists don't believe in an afterlife, many of them try to live this life at it's fullest. They too have loved ones, and if someone dear dies and you don't believe in an afterlife, it means you won't believe you'll meet them again.

Also, there tons of christian denominations, it's impossible not to fit in one of the many boxes if you're christian.