Matters of faith are matters of faith for a reason. They don’t meet the standards of evidence and explanation.
In the case of Christianity, we are forced to take the word of a small number of people whose accounts of events are inconsistent (as in the various books of the New Testament, which were written long after the events), conditions of observation are questionable (extraordinary events witnessed after days of starving in the wilderness), and predictions vague enough to be useless. “God” as an explanation depends on people internalizing the questionable stories and because of its subjectivity cannot be applied consistently or broadly (consider the differences in interpretation between, say, Baptists and Catholics).
Common replies to these issues are that the Bible is “the word of God” and that “God’s ways are mysterious.” How do we know that the authors of the Bible were controlled by God in their descriptions of events, except by taking someone’s word for it? That there is mystery is obvious; a credible explanation would dispel these mysteries.
Another retort to the deficiencies of sacred texts is that every other alternative depends on faith. Because none of us can comprehend and use all of the observations, tools, and explanations of science, for example, we must accept what scientists say on faith. This is wrong: we don’t HAVE to; it is simply convenient to do so in many situations. Any time we use a microprocessor, send a spacecraft to another planet, or fly an airplane, we are not only assuming that the theories and the observations that support them are correct, we are TESTING them. Testing of explanations (which is all that the theories of science are) is critical to their success or failure in favor of better ones. In matters of faith, people accept automatically that there can be no “better ones” and therefore are not inclined to perform rigorous tests of their beliefs.