Nobody knows what happens at death
I know what happens at death, I dont know the details. There is life after death.
There is life before death. We know it for sure, because I am alive NOW.
There is life after death. We know it for sure, because otherwise I would not have been born.
This is equivalent to "death is an event in time".
Since we know both facts it follows that death is the point where our state of knowing that we are alive NOW changes to the state of knowing that we were alive THEN. Hence we know that we are alive NOW and were alive THEN.
Observe, that we know that this change will happen in the future. And we know that after that change it will have had happened in the past. Thus death happens in the future and the past. This means that death is not an event, contrary to the assumption.