I would say I readily believe all of the claims in the Bible because I think hundreds of them have been documented, have been verified. Can you show me something that has been proven wrong from the Bible? Has an archaeologist proven anything wrong? They've discovered, like, the Hittite civilization. The Bible talked about the Hittites. Nobody heard of the Hittites for hundreds of years and all of a sudden, bing, they find evidence of the Hittites. Whoa!
I think the "improbable claims", all of the claims that I'm aware of in the Bible that can be verified have been verified. Some are yet still future. You'll see. Watch your knees. Next time you wash your knees, think "These things are gonna bow before Jesus Christ." Yes, they are.
Questionable sources; insufficient evidence? I think there's overwhelming evidence that the Bible is true. Now if you choose not to believe it (which is obviously what you've done), OK. I choose to believe it. But it's not questionable sources on insufficient evidence. You're the fool here.