The idea of the big bang isn't "science." Science is a philosophy. The idea of the big bang is a theory, one which has many convinced it is the most likely of the current candidates because a great deal of evidence seems to point that way. It is in no way a "certainty", nor would anyone who understands how science actually works be likely to say so. If you want to characterize it honestly, it is a "best estimate." No more than that.
I am more than a little disturbed when I observe people presenting the big bang theory as established fact. Nothing could be further from the truth. Doing so misstates the case, and furthermore, it dishonors science.
Theories are not "facts." They are intellectual structures built on observation, reproducibility, and the ability to falsify predictions. If we talk about Aristotle's error with the orange, and laud Newton for correcting that mistake... then we have to note that Einstein came along and corrected Newton, and the implication is that someone will very likely come along and correct Einstein (as the current state of quantum theory seems to imply) and so forth.
The sequence of events described by the big bang theory could be precisely what happened. Perhaps. But science isn't saying that. Science is saying that if there was a big bang, we think, given what we know today, that we'd see the following results. And mostly, that's what we're seeing. Could we be missing some important ideas and data? Certainly. Any scientist worth their weight in chicken droppings would admit this. Does that mean we should stop thinking about it, or using it as our best estimate? No, of course not. Not until it fails, as a theory, in some repeatable and definitive way.
I really wish more people understood how science works. It is not a realm of facts. It's a collection of ideas with varying levels of confidence that were arrived at using a tool for qualifying ideas called "the scientific method." Understand the method (not difficult at all), and you'll understand why science produces results. Misconstrue the collective theories of science as a factual description of the universe and all you've done is turned it into another religion.
Science mutates constantly, refines, performs triage on itself, etc. That is its strength. Today's reasonably high confidence result can be tomorrow's amusing story at the water cooler. Because these theories are not dogma, they are not fact, they are not "engraved in stone."
Think of science as a confidence building scheme. The highest confidence theories are those that interlock the most with other high confidence theories and which have the most ways they can be demonstrated, which give rise to the most testable predictions, and so forth. The big bang happened, if indeed it did, so long ago and so far away that we will probably never have access to anything but very old, very diffuse, and very secondary data. That is adequate cause for caution in assigning a high confidence level to any theory.
There are competing ideas out there in the realm of cosmology, some of them quite fascinating. If you have an interest, by all means, go check them out, study them. Just don't treat a theory like religion. Science's constantly tested and re-tested confidences are far more powerful than religion's inflexible dogmas will ever be. Science increases our knowledge, and it provides results, both positive and negative. The scientific method is easily the most powerful and effective tool humanity has come up with for building an understanding of everything around us. Our challenge is to use it well. Our record is mixed, sad to say.
Examining the big bang idea has led to all manner of new information about the universe. That is a more important result than it actually being correct in my opinion. As long as the scientific method is followed, the very people who are looking to bolster the big bang theory could be the ones to disprove it as they continually attempt to use the theory to make predictions and then test those predictions.
You can't ask for more than that; and you certainly won't find such behavior in religion. Your pastor isn't likely to wake up one day, waltz up to the pulpit, and inform your congregation that he prayed humbly and honestly and faithfully for X, X didn't occur, and he's now resigning to become a practicing atheist. A properly trained scientist, on the other hand, can and will turn on a dime when the prediction is X and the result is Y. That's why I'd rather have a scientist in my lifeboat than a priest.
Well, I suppose in extremis, one could eat the priest.