On at least two separate occasions in my personal life, and on many more while reading what theists have to say, I have come across an insidious argument which attempts to justify faith (through a rational argument, ironically enough!) by attempting to argue that every belief we have is grounded in faith. Here is my quick dismissal of this petulant argument:
The argument by the theists is that we have to take everything on faith, even reason. Besides the obvious objection here that they are simply trying to sneak faith in at the outset to justify faith according to reason, which is wildly circular, there is some epistemological justification for the attempt - there is no such thing as absolute proof. But in trying to undermine reason, they are forced to take this epistemological argument to absurd lengths. The major absurdity the theists run into is the attack on science. Science stands out as reason's crowning achievement, so to undermine reason requires undermining science. The theists resort to such arguments like, "even science relies on faith because every individual scientist is only familiar with the science which they have directly observed, and they have to take the word of all the other scientists regarding every other relevant piece of information even within their own fields, to say nothing of all the other fields. So science relies on faith, so reason does too, and faith is therefore justified". The obvious problem with this argument is that science works. Each individual scientist does not take the word of other scientists on faith alone; the method itself is proven reliable in each instance. Plus every experiment must be verified by other scientists. The fact that there are so many scientists participating in science is a strength, not a weakness, of science. They form an interconnecting web of support, as opposed to creating holes in an otherwise perfect medium. It is social epistemology par excellance.
It is also worth pointing out that in trying to undermine our epistemological justification in reason itself and, by extension, science, it can be said that the theists don't have much faith in science and reason. This is really the point, because these things are in direct opposition to faith, and so they must have faith in faith, which is to say nothing other than to believe that it is really okay to believe whatever it is that, in the end, they really want to believe. But in trying to use reason to justify faith, they really just end up showing how little they really believe what they are actually arguing for. I.e., if reason itself is unjustified other than on faith, and faith is rationally justified, then faith is as unjustified as the reasoning used to support it. But apparently, this point is completely lost on them.