It is a valid theory which makes it a true theory. However we do not have the technological insight to prove it. Which is why it is a theory. However, from what we have learned so far, it appears to to have more evidence behind it than what Moses wrote about in the Bible. The difference between scientists and religious fanatics is that scientists like being proved wrong. It gets them closer to the truth. Religious fanatics feel threatened by the possibility of being wrong. It gets them closer to the truth.
The big bang theory is most likely to be true but we won't know for a long while that's the creation if the universe ... Some aspects may be off. We do know how the earth and stars and other planets are made but I'm in my iPod so I can't type with my finger all that info
Theories cannot be truth because they cannot be proven. The Big Bang Theory is the most widely accepted theory in the scientific community. That does not make it true, but it does make it relevant. So believe what you want, but at least know how the theory works.