It is not difficult to find online forums and blog posts that proclaim facts and arguments as if they were certain. People of all philosophical alignments will do this. Theists will proclaim what they believe to be indisputable facts like: "Something must have caused the Big Bang", and atheists are often guilty of prophetically declaring their favourite origin story for the universe: "Quantum fluctuations produced the universe" or "Many-worlds explains fine-tuning".
It is almost certainly the case that time behaved differently at the Big Bang singularity to how it does now, and that it is not possible to define a time "before the Big Bang". Defining a time before the universe would be nonsensical anyway because time is a part of the universe, not external to it.