...if your a true Atheist, you rejected this thought for a reason. Perhaps the reason is, Heaven and Hell cannot be proven. Not believing in something that cannot be proven really has more merit than believing in something that cannot be proved.
I'm not sure there is much ranking or devoutness to the atheistic mindframe; that is to say, no "true atheist" need be "reasonable" to come to his/her conclusion. Just my opinion, though.
In light of this, i would further propose that the insinuated "rejection" of the afterlife, more specifically a
prescribed afterlife is more distastful or unfeasable as a stand-alone concept than a blanket religious dismissal.
It's not necessarily a matter of
1)-"there's no definitive proof of god, thus i shan't beleive"
But perhaps (in some cases)
2)-"you want me to beleive
what?"
You may have noticed that some atheists respond more directly (or venomously) to specific religions, perhaps flagging that which they have experience with. Others, i think, may just be demonstrating honest incredulity; we've not all been knee-deep in christians all our lives, and the implication that our denial of such concepts is at odds with the larger social fabric doesn't seem to universally apply.
Bear in mind that we ALSO likely reject countless other dieties and myths similarly, not necessarilly
just yours.
Go back in time 600 years ago. People thought the world was flat. If you lived in that time with the same mindset you have today, you cannot deny that you would have believed the world was flat because it could not be proven the world was round at that time.
I fully aknowledge that i probably think many wrongheaded things regarding the nature and truth of the universe, nor do i think myself foolish for being ignorant of what is currently undiscovered.
I WOULD resent, in such a situation, the threat of eternal torment based on a 'guess' as to whether or not the earth was flat.
If you are right that there is no after life, you won't know your right, but if your wrong about this, you will have an eternity to think about your decision.
It's very generous of you to give us such a stretch to ponder what will be very quickly evident. Beats the open book test by a long shot.