There are at least two things wrong about Paul Pardi's analysis of Christianity in this article. He claims that Christianity should be kept private by those who believe it because it's known by an irrational method - faith - that isn't accessible by everyone.
First, we don't know about Christianity by faith. Everyone knows about the claims of Christianity and the Bible in the same ways other things are known. Faith isn't a way of knowing. It's trusting in what we have come to know to be true. Faith is laying hold personally of what is true in the Bible. Knowledge is the first step and it's no different than coming to know about anything else. So it can be discussed between those who have faith and those who don't because they're both operating in the same way to evaluate truth claims. Faith comes after knowing.
Second, Christianity isn't a private topic. This is a way to subjectivize Christianity - to relativize what Christians believe. But essential to the what the Bible teaches is that it's not subjective or relative. It's true for all people. Things happened in history that were witnessed and reported. And what the Bible teaches is for all people. So engage in consideration of the truth claims of Christianity, but don't dismiss them as private, subjective beliefs.