"Can you prove that God (the God of the Bible) exists without using the Bible?"
Asking a Christian this question is asking him to deny his faith. It's asking me to lay aside my worldview to "prove" that my worldview is correct.
The problem with this is that if I were to lay aside my worldview to "prove" its validity, I would be admitting that I did not believe that that my worldview is sufficient.
This would be a direct denial of the worldview and faith I claim to hold to.
It's as nonsensical as George Bush's bid to "save" the free market by "sacrificing free-market principles," only the stakes are much, much higher than a mere nation's economy. As soon as these words left his lips (and his actions were consistent with his words), he could no longer be said to believe in the free market in any meaningful way.
It would be like asking a rationalist to lay aside reason, or an empiricist to lay aside experience. That would be unthinkable, yet this exact thing is demanded of Christians all of the time.
To lay aside one's worldview in an attempt to "prove" it is to admit defeat from the beginning.
Christian, don't surrender (and therefore deny) your worldview to "prove" it.
To do so is to deny it... and nothing is more painful than hearing that rooster crow.