That is because the ultimate beginning is something that is a matter of faith on both sides. Personally, I think those of us who are religious are more intellectually honest about that than the other side.
Personally, I'm not a big supporter of the thought of the universe being only 5k years old, though there is no way to prove the entire universe is more than 5 minutes old. Ultimately, I think it's unknowable, and above my pay grade. I wasn't there when the foundations of the Earth was laid.
That was from Stein’s documentary “Expelled.” The conversation you’re referencing was near the end with Richard Dawkins.
I saw it in the theater at the time it was out, it is very good, check it out if you can find it.