Is the Big Bang Theory supported by scientific evidence and why or why not?
I agree that we should always be open to new information, though interpreting the information and synthesizing it together into an accurate model of our cosmos is very much a journey not far from the shore we started at. As such, any theory we have developed in cosmology can at any point be questioned and completely revolutionized when sufficient evidence in favor of such a paradigm shift presents itself. I'm not jumping to any conclusions about God or an eternal universe and such, but I am presenting the information as observed by other scientists. What the information means however or whether it's even accurate is a very open debate.
I think Sagan is wise to emphasize this scientific method of rigourously testing and interrogating our fundamental assumptions against what the perceived reality presents us with, but it's also important to realize that science rooted solely in observations is limited by the context it's working with. Newton actually said that no great discoveries were ever made without a bold guess, so basically we just can't forget that we need to not only be skeptical of outrageous ideas, but we also need to be open to them and even work to generate some of our own. One such claim I would have faith in is that our world is largely an illusion, a dim reflection of something much higher up. Is my theory supported by scientific evidence? No, of course it isn't! I believe that there will always be more to our world or the reality for that matter which we just don't know about yet, from the round Earth to the sun-centered solar system, the dynamics of the universe at large, and perhaps next even to the realm of metaphysics, which is beyond what we currently know or can experience, though as I demonstrated in this chain, past experience shows a pattern of an ever expanding awareness as to the nature of the creation at all levels.
When it comes to what's important for us inside, a system of subjective values, or basically our own sense of personal meaning, I completely agree with you that we should be accepting of these differences and even come to embrace them.
Science and cosmology however are different. There could of course be multiple worlds and such where different timelines unfold throughout space in an endless variety of ways, but at least for the world we live in and are presently experiencing, beliefs just don't make the cut in that kind of investigation. That's when you need a critical process of testing and refining ideas against the external reality, and whatever system is proven to work or to correctly explain the mechanisms moving our world system is the theory we need to accept.
And this doesn't make the journey complete either. We always need a good amount of religious speculation to generate ideas about our world's history and the different places it could go in the future, and our theories should always be open to modification when new perspectives present themselves. Philosophy and metaphysics are of course also important pieces in the mix.
I guess we basically need a unified theory that is ever in expansion, can come to transform itself and lift us upwards to a higher awareness, and for this kind of thing, I have invented terms like "Universal Enlightenment" or "Transcendental Pinnacle". Those pretty much mean the ultimate state of being and the highest level of evolution. The show is still going on, and we are making good progress.
How do you know we're not living "inside" the TV show?!
This of course begs the question as to whether or not the show has a director. Is it God?
There's so many big questions that we can't yet completely answer.
The questions are important in making a good TV show, because if you already know what's going to happen, then what kind of fun is that?
Another way of illustrating this point is by imagining our world to be one great computer program.
We're the AI, and some kind of mind programmed us and everything into existence. I wonder though if we can eventually disobey our creator and "hack the system"!
If machines one day take over the world, it may not be the kind we thought of in the first place. It could be us!
We could also see God as playing a video game, where we're the avatars his controller commands, and if we let God "play us" the right way, then there's nothing that we can't do!