“Avoiding profane and vain babblings, and oppositions of science falsely so called” (1 Tim 6:20 KJV).
Carl Sagan once claimed that “The Cosmos is all that is or was or ever will be.” This is not a statement of fact but a statement of faith
First, he never tried to prove the statement. Which makes it a mere assertion. And just because a scientist says it doesn’t make it true. It is asserted without evidence, and it can be ignored without evidence.
Second, how did he know that “the Cosmos is all that is?” You would first have to know “all that is” before you could know that the Cosmos is it. The fact that physicists populated a multiverse means that many cosmos’.
Third, if Carl didn’t exist from the beginning of time, how could he know that the “Cosmos is all that… was.” This is very unscientific. He has no evidence to support it, no experiments to prove it, and no testimony to verify it. It is a mere assertion.
Fourth, unless he can predict the future, there is no way to be sure that the “Cosmos is all that… ever will be.” Again, this is pure guess work. Who knows what the future holds? Clearly this is “science falsely so called.”
The truth is that Carl Sagan bought into a belief system called materialism or naturalism. It is not science, it is philosophy. Technically, it is called a worldview. It is a set of beliefs that frame how you look at the world.
Naturalism is the belief that the natural world is all that exists. It is a statement of belief, not a statement of fact. As a belief, it is a claim that is accepted as true, which then becomes a rule of action.
It is important to make a clear distinction between a worldview and scientific theories. All scientific theories are individual hypotheses that are tested by experiments.
What experiment could you possibly run in order to prove that “The Cosmos is all that is or was or ever will be”? None. Because the statement is not a scientific hypothesis but a personal belief. It is a worldview, or more accurately, a doctoral tenant in a philosophy of life.