I completely agree, if it's simply warrant we're talking about for certain types of beliefs. I completely agree. When I was I married and someone could have asked me to prove that my wife at the time wasn't cheating on me because after all im not with her a 100% of time? I would have simply asked "can you give some reason to doubt that"? If no than i have complete warrant to not believe the statement. That fine and true but the warrant system can't work for all questions, like in what world (Christian, Muslim, Buddhist) does warrant epistemology even make sense?
This is the one gotcha trick of Van Til. We know Christian theism to be true therefore everything is as it is because it's true. I don't know how a critic of Van Til, not saying that he or you are, could possibly object to that? The rest of his method builds upon that truth.