Saying we think any science result is infallible is just ridiculous we are always skeptical of eveything as scientists.
I study, teach and scientifically challenge the big bang not because it is guaranteed correct but because it is our best understanding at the moment.
I also teach Newtonian physics yet I can prove to you that it blatantly wrong F=MA only at very small speeds and accelerations.
If I could only teach that science that was abolutely correct I could teach nothing because there is no single fact that is absolute and guaranteed correct.
The big bang represents the most consistant story that agrees with all the observations and that is why we teach it.
I personally don't believe it, my problem with it is QM. I have come to believe QM is far more fundemental than SR/GR and that changes everything at the big bang.
I am not alone in this belief what we see is QM sets up "proper time" not the GR/SR distorted time you and I see. We have no proof and we are setting out experiments to test this (
http://www.physorg.com/news/2011-10-clock-quantum-mechanics-relativity.html). These are very expenisve experiments to set up so we must show others why we believe these things and of coarse what we suggest must be compatable with all current observations.
So saying science believes the big bang is infallible is just plain wrong there are many of us challenging it but I can not show you one observation that is inconsistant with it but I am trying to create an observation that is inconsistant with it.
Our version of the big bang under QM is well interesting because you don't come from nothing but you do come from something outside the physical universe.
