Dualism does not Help the Afterlife
According to substance dualism, the mind is an immaterial entity, existing independent of the body. People typically take dualism to be more amenable to an afterlife than its alternatives, but I don't think that this is true.
In the typical Western picture of the afterlife, you're still in possession of all your faculties. You can think and reason. You remember your earthly experiences and relationships, something of your personality remains. You may be in Heaven or Hell, but you're still the same old girl you used to be.
But, regardless of whether dualism is true, we know these things depend on the proper functioning of our brains. Amnesia can be caused by drugs or brain injuries, brain ischemia often leads to dementia and personality changes. So, when the brain dies, we can't imagine that any of these things endure--if they did, it would be a miracle. And, of course, the dualist is free to say that the afterlife is miraculous. But, if she does, it's unclear how dualism is helping anything. You could just as easily be a physicalist and say that God miraculously sustains our mental lives.