Tertullian's Paradox

Reading Tertullian's Paradox, I stumbled upon a quote that I found incredibly intriguing in light of the entire semester in Philosophy of Religion.  Williams says, 

"For here again the initial faith is in a belief that is itself comprehensible: the belief that the poem has a meaning, if one can only find it. But in the case of religious belief it is just the belief itself, and not a prior belief about its comprehensibility, that one has, on the position being discussed, to take on faith, in the hope that afterwards it will become clear what it means. Here again I encounter the same difficulty: for if you do not know what it is you are believing on faith, how can you be sure that you are believing anything? And a fortiori how can such belief be the means to something else, viz. coming to understand?"

What Tertullian proposes is that we must engage a paradox. Tertullian's Paradox has a lot to do with the idea that we are to be like Christ by not being like him. He was put to shame, we are no longer shameful and examples of the like.  It is that to be as Christ wants us to be, we need not be like Christ necessarily. The paradox extends into knowledge. Simply because the resurrection is impossible to believe by any type of evidentiary proof we must believe it! He says of the resurrection, "It is certain because it is impossible!"

Now what I find here is that Williams takes this claim, that on faith one must accept the tenets of Christianity to understand Christianity at all, and 'pulls an Anselm', so to speak.  I have found myself incredibly frustrated in the mire of Anselm's writings.  In my estimation, Anselm sees faith as a starting point to a greater understanding and knowledge whereby faith is no longer needed, but simply was a prerequisite to something much greater.

I see much of that thought in Williams' interpretation of Christianity and the paradox here. What Williams'
want is a prerequisite of believability or credence before he would accept anything like a resurrection.  As we have seen with Kierkegaard, his willingness to believe based on scholarly deliberation is useless.  However, if he is right that Tertullian is Anslem-like in his paradox, I am again perplexed. Williams does say in the aforementioned quote that faith is to believe in the incomprehensible.  How he manages to move from that to "if you do not know what it is you are believing on faith, how can you be sure you are believing anything?" in two sentences is beyond me.  To answer his question, it's not a matter of believing that, rather a believing in (excuse my ending in a preposition). Williams disregards that to believe, for the Christian, is to trust there is a God who saves. Williams clearly wants a Christianity who believes there is a God, empirically proven.  I find it truly frustrating that he can not comprehend that faith is not an empirical proof and we do not move from faith to knowledge, casting faith aside.

At a loss for a better conclusion, I will leave these as the Barthian in A.N. Pryor's dialogue, with a Scripture:

...They have stumbled over the stumbling stone, as it is written,
“Behold, I am laying in Zion a stone of stumbling, and a rock of offense;
and whoever believes in him will not be put to shame.”
(Romans 9:32-33 ESV)