Excellent post. I will study in detail later but a quick comment for now.Another good question...perhaps I should take a stab at producing a methodology for determining truth in the context of my understanding of Christianity in the broadest sense and then I can answer that question...
My own understanding of what is the central belief in Christianity is that Jesus Christ died for my (our) sins. I would assume that most believers in this see this as a literal statement of truth. I see it as a metaphorical statement of truth and it may be that that is not an uncommon way for some Christians to understand it even if they believe that it is essential that Jesus' death and crucifixion must be a historical fact. But this belief is NOT a methodology or epistemology. How should we understand it as such?
This belief comes into play when we engage in "self talk". Self talk is a term used in psychology to reference that inner dialogue which takes place in all of us automatically. It is our minds automatic thinking especially in a sort of dialogue form as if what we are mentally were a variety of voices all contributing to our self-awareness of our understanding or processing of our past, present or anticipated experience. Within that sphere of mental experience we have a notion of God who as a "higher personality" is aware of all of this inner conversation and can even contribute to it (somehow). So by engaging in this inner dialogue with the belief that God is present, we help to enable a sort of responsible inner monitoring of that same dialogue...that is, we are inspired to take moral care with respect to what is going on in our heads. This is, after all, a precursor to action or the process of determining available options should choice become necessary at some point.
Now Jesus is interesting in that he represents an intermediary between God and our selves. We can identify or empathize with Jesus but no so much with God. God, after all, created all those things that burden us. But Jesus was a "real guy" who lived and suffered as we do. As the story goes Jesus lived as a good person but was falsely accused of being deeply evil and punished by the religious and the civil order of his society. As a result God restored him to life after dying...God freed Jesus from the burden of everlasting death whatever that means but apparently didn't restore his physical existence on Earth.
So how does this impact one's sense of management of one's self talk? It means that no matter how harsh or condemning one's own inner voices are toward one's self one can still find favor with God if one listens to God's Word. Jesus demonstrates this through his teachings and the "sanctification" of his teachings through the story of how he arose from the dead in spite of it all. Only God could have delivered Jesus therefore what Jesus taught is in accord with what God wants for us.
As such we are given the gift, in the monitoring of our self talk, to seek forgiveness for anything which we might have done that causes us to feel bad about ourselves. This is a huge boon in the realm of our managing of our self talk when society offers only punishment, condemnation and even death for the truth of what we might have done or wanted to do. It also can come in handy when one is convinced one is not worthy in a variety of ways. When contemplating the story of Jesus and his teachings we are to see a light at the end of the tunnel of any suffering. And Jesus' suffering was clearly great as featured in the special narrative of the Passion of Christ.
Now again for me, it is not necessary to believe that this all literally happened. It is enough for me to believe that the story is metaphorically true in that we are all never beyond redemption not only in our own minds but in the minds of our society if we but have the right action and attitude towards ourselves and others. In my own dream experience I have, on a couple of occasions, found out my guilt and submitted to a sense of morality beyond my own personal need in humility. That has consequently given me a lasting personal freedom and compassion for others.
I should mention that there are some egregious abuses of this story, most notably in the form of the whole believe or go to Hell attitude which I find virtually Satanic in this context. That approach has forever stained the value of the one that I described above.
So I think that in my understanding of Christianity I am not alone...if I mask some of the mechanics of it. If I don't then I may burst some of the fantasy bubble of the narrative that many people have not the confidence level or scientific background to be able to integrate into their own understanding.
Here you present the Christian belief as a mode of self-development or psychological healing...for want of a better term.
How does such a practice relate to truth per se? For example...one may justifiably claim that jogging is a reliable way of fitness development. But saying jogging is a way of finding truth makes no sense at all. So, currently, it seems to me that science and religion, by your description, are about quite different things. Religious practice is a set of practices for improving the health of the mind, and science is about finding the most useful and reliable models about the workings of the world.