Erm, no, not according to my understanding. Cosmic inflation (aka big bang) was determined by empirical measurement, via red shifting among other things. Dark Matter/Dark Energy was discovered via other tests.
So, at one point, there was the Big Bang model sans Dark matter/energy.
You are mistaken, I’m less sure of the latter two, but there were many empirical tests (red shifting being one) that led to the conclusion of the Big Bang. It’s also a consequence of the theory of relativity (IIRC).
I believe they already are tangible, but to compare them to Christianity seems grossly misguided. Would you have compared Copernican heliocentricism to Christianity?