I'm not so much hung up on the idea of an 'afterlife' as I am on the notion of 'forever.' If you've ever tried to crawl all the way up inside that concept, you know it's terrifying.
One hundred and eighty million years could pass one hundred and eighty million times, and not even nick the surface of 'forever,' because forever is infinite.
Even to be in heaven, or any pleasant place for that matter, 'forever' is still an absolutely terrifying thing to contemplate. Human beings are linear. We're finite, having a beginning and an end. Our minds are also linear, and can comprehend finite things--things with beginnings and ends. Try to comprehend something that is infinite, and a human being can approach madness.
An afterlife is to exist after death. It's a state of being. I can handle that. The duration, if it's forever, that I can't handle.