What Does It Mean To Be Open-Minded? Or Closed-Minded?
There are two problems we face in order to cultivate the intellectual virtue of open-mindedness. The first is to learn what constitutes evidence, since most people are unreasonably persuaded because of anecdotal evidence, or fallacious arguments substituting for the lack of evidence, or even peer-pressure or the accidents of birth into a particular family or a different culture. The second is to learn to avoid confirmation bias as much as possible, which Michael Shermer calls "the mother of all biases." [In The Believing Brain, p. 259].
When it comes to investigating the truth of a religion, open-minded people will reject faith-based subjective private states of the mind in favor of objective scientific evidence. Open-minded people who honestly want to know the truth will consider the evidence as dispassionately as possible, using no double standards. They will do so from the perspective of an outsider in the same way they already reasonably investigate all other religions (which is what The Outsider Test for Faith
So when we see Christian defense lawyers like Victor Reppert, David Marshall, Randal Rauser, Thomas Talbott, Mark M. Hanna, Norman Geisler, Matthew Flannagan, Steve Lovell, and others argue differently, you're seeing how faith interrupts the rational thought processes of otherwise intelligent people. Because that's what faith does. Faith itself is a cognitive bias causing people to misjudge the probabilities in favor of one's own faith.
For my part I have a really hard time respecting these Christian defenders, since it's very clear they are not being intellectually honest. If they were intellectually honest they would admit this is the best and only way to know which religion is true, if there is one, and then proceed to argue that their faith is true.
The fact that their God created the Christian faith such that it fails this test, if it does (and I think it does), is not the fault of the test itself! Just imagine if their God exists and made their faith pass the test? Then they would be the one's advocating it, not me. You know it. I know it. Everyone knows it. You will never see more closed-minded people who will all swear up and down to a fault that they are open-minded. If there is any better way to see my point that all Christian apologetics is special pleading, as I argued in chapter 7 of How to Defend the Christian Faith: Advice from an Atheist, then I don't know what that would be.
If you're now willing to be open-minded then this book, Christianity in the Light of Science: Critically Examining the World's Largest Religion, will be a great place to start.