I agree that religion is poisonous, but I wouldn't use those exact words. Religion is potentially dangerous because it asks you to give up your reason in exchange for faith. Without reason, one loses the ability to live in accordance to reality.

Why even ask if a world can exist without duality? It would be a world breaking its own logic and properties. That being cold can also be hot. And being large can also be small. It would be an existence that isn't possible.