Considering God represents Ultimate Reality, and that if the Ultimate Reality is that no God exists, then that is still God existing since that is the Ultimate Reality, and God represents Ultimate Reality.
If we say Ultimate Reality doesn't exist, then that is our view of Ultimate Reality. Doesn't seem possible anyone can get away from that. Everyone has a view of that, regardless of what they believe about it.
How we understand what that God is, that Ultimate Reality, is the only thing that changes. But ultimate truth is still ultimate truth, no matter how we think of it, be that in terms of theism, agnosticism, pantheism, panenthiesm, or atheism. It's all still a view of God, or Ultimate Reality, despite all protests otherwise.
As far as the question of the afterlife, I think one has to first define what Life is, and secondly what or who "I" or "self" is.
Personally, I think all there is is Life, and it is not possible for Life to not be in some form or another eternally. Therefore, there is no "after" life. There is only Life in different forms. It is Life in all forms, past, present, and future from our perspectives, whether that's you, me, my parents, my children, my dog, the trees, extra-terrestrials, etc. It is One and Many. Therefore, there can be no "after" nor a "before" to what just simply IS eternally.
From the perspective of individual forms however considering its form as it is, none of that if fixed either. As a 50 year old, a person is not a 5 year old. The body today is not the same body as it was when we were 5, yet we see it as the same body. In reality, that 50 year old is the "afterlife" for that 5 year old.
In fact, on that 5 year old's happy birthday, blowing out his candles on his cake and then going to bed that night, the next day is the afterlife to that child from the day before. And so on.
If we self-identify as the physical body, with its bones and cells and tissues, then every passing second sees the passing away and rebirth of that. If we self-identify with our personalities, then that too passess away and is reborn anew throughout our physical lifetimes. So what then signifies "death"? What signifies "life"?
You see the challenge of this question? It's not so simple to say when this body dies, that "we" die. As I see all forms as that single Life, in constantly changing forms in each and every passing moment in time, physical death of the body is simply another change of the form into a state of dissolution and decay. Where was "I" residing before in all those myriad change-states during the body's lifespan? In the cells? In the liver? In the brain?
It really comes down to identifying the seat or the locus of self-identification, and then going from there. When someone speaks of the "afterlife" in a religious sense, who are they seeing themselves as in their self-identity? If they are imagining walking about in heaven on two legs and having their dog restored to them with their new heavenly house with new gold paint, then they are identifying with their egos in this life, as the ultimate truth of themselves.