It's "Jeff Dee", by the way.
Atheism is the lack of belief in gods. All evidence is that there is no afterlife and that when we die, we cease to exist. What do you think, exactly, is going to change its mind? My decomposing body? I suppose that every inanimate object is atheist as it would not have the capacity for belief in gods.
I should probably turn the question around on you and ask why you think you might continue believing after you've decomposed.
If you have evidence for an afterlife (beyond it being popular wishful thinking), please present it. I have no concern about the veiled threats that believers would like to hold over atheists. I can only imagine that they choose to worship a thug god without evidence because of their own deep character flaws.
Finally, as for "following atheism", there's nothing to follow. Atheism is a single position on a single claim: that some god exists. Atheism doesn't have dogma and tenets. I don't know whether atheists are more likely to donate their bodies to science or not. I imagine they do at a higher rate than theists, who might believe in a bodily resurrection. My wishes are for organ donation and cremation, but these are personal decisions that each person makes.
The sad fact is that the living relatives often make decisions on behalf of the person who died. If a person doesn't make their wishes clear, their relatives are likely to "go with the flow" and chose the default death arrangements for the deceased. This is certainly one place where the religions are happy to step in and use the event to advance their cause. I personally consider this behavior despicable.
