As an atheist I find such a doctrine utterly absurd on so many levels. For one thing there's no evidence of either a God; nor is there any proof of an afterlife, let alone one in the sky populated by harp-playing angels and streets of gold or alternatively, the other at the center of the earth filled with souls writhing in fire and brimstone. Then there are those who project "the next life" as a continuation of our current existence. I know a woman who every year wishes her deceased mother a happy birthday in heaven. Then there are those who think that they will be reunited with their departed loved ones.
These are the images of eternity with which Americans and other Western world people (especially Christians) are most familiar and in which they are likely to believe. However, this set of fables is just one of many myths of life after death which are equal to the number of religions throughout the world. They can't all be right, but most of their respective adherents claim that their particular version is the only real one.
I have considered another and more sublime scenario that awaits us when we die and one that sounds reasonable: We know of course that our bodies decompose and our minds cease to function. But beyond that we disintegrate into the scattered atoms that constitute the elements of the universe from which we were formed individually and to which we will return. From there they may combine with other animate and inanimate substances alike. Further, this process will continue as long as the universe exists—most likely at least several billion more years—which is as close to immortality as we can hope to achieve. As Carl Sagan put it: "The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made from interiors of collapsing stars. We are made of starstuff."
On a personal level, IMO there is no reason to worry about death. In the words of Mark Twain: “I do not fear death. I had been dead for billions and billions of years before I was born, and had not suffered the slightest inconvenience from it.” Nor do we have reason to believe that we will do so after we're gone.