If a bunch of geologists got together and agreed the Grand Canyon was 30 million years old, would that make it true?
Of course not, no more so than a bunch of priests getting together and agreeing that the universe was 6,000 years old would make it true.
On the other hand, if the geologists could present convincing evidence in peer-challenged scientific journals that the Grand Canyon was 30 million years old, why wouldn't you believe it?
Likewise, if the priests can present convincing evidence in peer-challenged scientific journals that the universe is only 6,000 years old, I'd be happy to believe that.
Mind you, they'd have to present far more evidence, since this would contradict virtually everything we know about physics, geology, astronomy, biology, etc.