retrofuturist wrote: Are Buddhist beliefs "unjustifiable", for example?
Some, yes. And in fact no different than in some other religions.
Ex: Fish 5,000km in length. City existing for 100,000 of years... Rain being caused (always or sometimes?) by devas.
Also the idea of Kamma from past lives (some of them long time ago) , while being better than Theistic beliefs, is not much more provable/verifiable than God/Satan handing out the punishment.
Many people reject the Christian idea of hell with demons and boiling pots of water, etc, etc. And yet this is found in the suttas.
There are many truths in the suttas. But just because someone was right 9/10, it doesn't make him/her right the 10th time.