What makes this situation worse is that the religious person has absolutely no idea when he is making untrue statements. He or she has been raised to think that choosing "facts" based on how he or she feels about them is not only perfectly normal and acceptable but a positive virtue in many cases.
In fact, religious people invariably assume that this sort of "rationalizing" approach to thinking is the norm. This is one of the reasons they so often accuse non-believers of rejecting god because they don't want to follow god's rules. They assume that we, too, are simply rationalizing our pre-formed desires.
In my opinion this sort of argument is another of those non-arguments in which the religious are implicitly admitting that they know their beliefs are delusions. At the very least, they are admitting to rationalizing--especially if they say they think you are doing it because that is what everybody does.
If they do say such a thing to you, try to get them to admit that they have just implicitly admitted that this is how they think about religion. That they are rationalizing their desires rather than rationally seeking the truth.
Then, you can quote or paraphrase Richard Feynman, who said in a lecture in 1964 (speaking about the scientific process):
"The first principle is that you must not fool yourself, and you are the easiest person to fool."One of the best paraphrases of this that I have heard came from Prof. Lawrence Krauss, who rendered it as "the easiest person to fool is yourself".
If need be, you can follow up by explaining that fooling yourself (rationalizing) can have deadly real world consequences. Feynman was on the committee that investigated the Challenger disaster in the 1980's. In the committee's report there is a sentence that has Feynman's imprint:
"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."Science provides the tools--the process--to avoid fooling oneself and avoid the inevitable disaster when nature is not fooled. That process is infinitely superior to the one taken by the religious mindset, which is that something is true only if they want it to be true.