How do you get through to a religionist that atheists aren't scary, evil, uninformed or immoral without the conversation degenerating into angry shouts and flaring tempers? Over the years, I've found that trying to stay calm, rational and focused on the issues works much better than direct confrontation and blithe dismissal of the believer's errors.
One idea that I've developed over the years is that a person's religious and political views end up not only coloring how they interact with the world, but also how they see and define themselves. In most households, religion is a permeating and everpresent fog that envelopes a child from the day he is born until the day he sets off to college (or work, or wherever). In such a climate, it is natural not only that an individual gathers in the views and opinions of his parents, but also that such views and opinions will come to define the image of "self". Being told time and again that one is a "Christian" or "Muslim", while seemingly innocuous, is actually forcing a child into a mold that didn't previously exist -- and is damningly difficult to escape from.
After a while, especially in a strict fundamentalist upbringing, those beliefs come to define the person. When later in life such a person is challenged about their religion or beliefs, the believer sees them as questions or attacks on not just the religion, but on the person. This is one of the most insidious and diabolical ways that religion pervades, infiltrates and takes over minds. By coopting the egotistical and natural sense of self-protection, religions can avoid direct challenge and argument.
However, this can leave the believer in a very tenuous state. If their entire sense of self-worth and self-image is tied so tightly to their religion that the two become essentially unified, then any perceived or real error, mistake, or omission in the religion becomes an error, mistake or omission within themselves, too. This is how fundamentalism and dogma assert themselves, and it takes a lot of patience, trust and time to overcome. Most YECs fall into this mold - and anyone else who is taught that their "holy book" is innerent and infalliable.
So, how does one deal with such people?
I've found over the years that you have to take things very slow. If you wade in from the start with a whole list of errors and mistakes from their holy texts, you'll never make any progress. All such frontal assaults will do is cause the believer to throw up an impenetrable wall that cuts off any chance of communication and rationality. Not only that, it will just reinforce what he or she has always been told about "unbelievers" -- that we're trying to get them to go to hell, too.
I prefer to start with trying to understand the believer as a person, and ask "searching" questions to get a dialogue going. Although I might have an answer I'm satisfied with, this allows me to express an interest in the believer's views and show that I've got respect for them as a person. It also can, if done skillfully, push the believer to begin to rationally and critically examine their beliefs in a safer, less confrontational setting. Usually, I start with tangential issues -- I never challenge them to "prove there is a God", because 1) that's not realistic, and 2) it ends up pissing them off, and they end up throwing up their wall of silence again.
Instead, I try to get to know them, gauge how deeply held their beliefs are, and try to find out what areas they are themselves somewhat uncertain or curious about. This not only leads to a shared experience, but generates some beginnings of trust and mutual respect that are essential when dealing with a person's self-esteem and ego. Depending on the level of discussion and the frequency, as well as how deeply embedded their beliefs are within themselves, getting fundamentalists to take those first steps onto the path of rationality and reason can be a frustratingly long process. I've personally "converted" a few -- and in each case, it took patience and a lot of time. You have to start with small victories and work your way up to the larger ones. In the end, most didn't fully drop their religion, but what they had was a less restrictive and more accepting version that allowed them the freedom and self-confidence to travel their own path, and to generate their own questions and challenges without fear of destroying who they thought they were.
Just getting a YEC or strict fundamentalist Muslim to admit that their holy books might not be perfect and innerent is huge. It might not seem like much to most, but that is the critical -- and necessary -- first step. If they can accept that just because their Bible or Koran isn't perfect, that it's not a reflection of imperfection in themselves, then they are on the path to a freer, more open dialogue and understanding of the universe. By severing that "belief=self" connection, the religionist is then able to begin the ardurous and often painful process of shedding the strictures and bindings of religion, and they begin to see the possibilities and beauty of life without faith.