My answer to the title is, peacefully, painlessly, unrepentingly, fearlessly and unquestioningly. Preferably attended by some good music, a heavy dose of sedatives plus one’s favorite intoxicant, and one’s favorite company, treated to what they like at the to‐be‐deceased’s expense. Easily. Conveniently. Simply…
From the very start atheism is the joyful way to live. We are concerned with what we have while we live, the ones closest to us and truth. Not vague promises of afterlife, threats of purgatory or limbo or nonsensical beliefs designed to circumscribe what we are. We live in the now, do what actually counts and make the best of what we’ve got. Both for ourselves and those we care about. We live our life, and should definitely hesitate to waste any part of it—all an atheist’s got is this one life, with no promise of anything better, or beyond. So that life had damn well better count, or it would all have been in vain.
I think that sort of positive, all‐or‐nothing outlook is what should condition atheists’ passing as well. We’re not here to burden our closest ones. We’re certainly not here to harass other people over our medical concerns. We’re not here to force others to waste their resources in clinging to false promises of supernatural hope, the profound irrationalism that constitutes the miracle cure or even the mistaken notion that anybody has any real duties towards an inanimate cadaver. We’re here to live, and as long as death isn’t avoidable at reasonable cost, to die as well. We should embrace those facts and aim at making the cycle of life run as smoothly as it possibly can. Even in death, our loyalty should never center on the conventional theistic mindset of how things should run, but on that which truly counts. That’s the other people who are left behind to mourn, care for our residual messes and our corporeal remains.
I think an atheist’s only duty in death is to maximally unburden those who are left to live. When we cease to be, they still need to go on because they too have but one life to live.
The implication is, when we die our debts should be settled. We should pay for our own coffins. In case somebody bothers to attend a wake, it should constitute one bitch of a hoot. We should arrange for comprehensive and timely organ donation, our children’s future needs, spouses’ welfare and charity to the degree possible. We ought to arrange for whatever we leave behind to go to those who need and deserve it. That includes our bodies as well—those are just mindless matter after our consciousness ceases to be.
Most importantly we must say our goodbyes well beforehand and prepare our loved ones for the loss. We must let go before resorting to the endless uncertainty of overextended intensive care. We must never set any one‐sided conditions on how our possessions or our remains should be handled. In fact we should prepare other people to accept that we simply do not care: when us atheists die, we simply cease to exist. If our passing can in any way help those left behind, then that’s precisely what should happen and we should arrange for it. But it’s all just for the convenience of others. We have no rights over the residuals of our lives once we go. No matter how weird the outcomes might prove. I mean, who could care less at that point than us?
With regard to death, atheism is as simple as it gets: first we live and then we don’t. It’s also just about as life‐affirming as possible—one life is all us atheists have; reason is the main tool we’ve got to help us in living it well. So let’s use our brains while we still have them at our disposal. Let’s not hurt other people, but instead help them deal with the fact that we’ll one day be gone, as far as we can. Let’s help them know death isn’t such a bad thing when properly implemented, make their parts in our own demise as easy as possible, well beforehand, and make the best legally allowable use of what we leave behind, for the benefit of those who might still have something to gain from us.
An atheist should die with little fuss, responsibly and with the reassurance nothing but thorough preparation can bring about. In the end, death too is one of the things a rational mind needs to take into account. The only difference is that the concern is our final one.