I don't find it very weak.
The so-called prophecies that were fulfilled before we were born were not recognisez before the events either. Right?
And even if they were. Who garantees you that God is the only being with knowledge of the future and the past?
Who can garantee that it was God who gave those prophecies to humans?
It doesn't take much imagination to come up with a dozen of other explanations for the prophecies. I could tell you some very nice ones if you wanted.
I am afraid there is no proof for the divine-ness of the Bible. Sorry.