i may be way off and it might not make any sense, but if their is no 'afterlife', wouldnt life itself in a sense be eternal, obviously life does not last an eternity, but if there is not an afterlife then to the person living the life it would last an eternity (not 'eternity' in its literal meaning, couldnt think of a better word, but i hope u get the idea)because when they die everything would cease to exist, like humanity only lasts a lifetime.
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Eternal Nothingness is Okay if Your Dressed For It