Looks like Ecclesiastes is your source for this nonsense. Physical death is the SEPARATION of the soul and spirit from the body. While the body goes into the grave to become dust, the soul and spirit are imperishable. Therefore the righteous dead go to Heaven, and the unrighteous dead go to Sheol/Hades to await their final judgment. And there will be a resurrection unto life (for the righteous) and a resurrection unto damnation (for the unrighteous). Soul Sleep and Annihilationism are false doctrines promoted by the cults. So if you are in one of those cults, they will have many more false doctrines.
Ecclesiastes 9:3-6
This [is] an evil in all that is done under the sun: that one thing [happens] to all. Truly the hearts of the sons of men are full of evil; madness [is] in their hearts while they live, and after that [they go] to the dead. But for him who is joined to all the living there is hope, for a living dog is better than a dead lion.
For the living know that they will die; But the dead know nothing, And they have no more reward, For the memory of them is forgotten. Also their love, their hatred, and their envy have now perished;
Nevermore will they have a share In anything done under the sun.
yes
Solomon is talking about what goes on 'under the sun' - in our physical existence. he says tge dead ((physically)) have no more part in physical existence: they are forgotten and they do not inherit anything in the world and they don't know *specifically* anything about the fact they will die.
the spiritually dead likewise do not know they will be liable to the second death, they are not written in the book of remembrance, they do not inherit reward, and they have no knowledge of God.
If two dozen other passages refuting annihilation upon physical death didn't exist, then this one passage might rightfully be misinterpreted to mean that when a person or other animal dies, it ceases to exist. but there happen to be many other places in scripture that speak of those who have physically died as though they do indeed still exist, so the meaning of Ecclesiastes 9 must not contradict them.