I don't think he was saying that we can't know ANYTHING for sure. (Again, he can correct me if I'm wrong.) If you take out the word "biblical" and instead use a different word, such as "a priori" or "self-evident" then he's saying the same thing that CS Lewis said. And that other believers have said. And it's something that many atheists don't realize... They always try to say that science, or our physical senses, are the only way to determine truth. But what they don't realize is that you can't even begin the scientific method without certain philosophical truths being in place
first. And those are truths that science cannot prove, they are self-evident, or
a priori truths.
We can know that absolute truth exists. It doesn't have to be a matter of "faith." Because to deny it is illogical. And atheists who deny absolute truth have no leg to stand on when they make a truth claim, such as "god does not exist." If absolute truth doesn't exist, then their own statement (which is asserted as an absolute truth) cannot be true.
Maybe, maybe not.