Well, I may not be able to answer your questions. You have been at this a long time and still have not come to a conclusion. By your own admission it is not because you are ignorant. I will be glad to respond to one question per email. Your last was:
"How can you know you are "finally and immutably" right.
Of course I cannot. Faith is the hope of things unseen. It is my position and I have bet my soul on it. But in that sense I am no different than a Mormon or a Hindu or anyone else. However I have not come to my conclusion without evidence. And the pathway looks something like this:
1. I came to believe that there is a rational, creator God Who is responsible for my existence.
2. It seems reasonable to spend my life attempting to know Him and His will for me.
3. A rational God, I presumed, would not create us and then fail to communicate with us.
4. After much study and many side trips (including Mormonism) I concluded that He had communicated with us in the Bible (offering many proofs of its veracity including Fulfilling Prophecy, Archaeology, Wisdom, etc. I did not find these same evidences in the Koran, the Vedas, or other philosophies I looked into.)
5. I found that idea that this God Who bothered to communicate with us would allow man to destroy His communication. In other words I felt that if He Gave His precious Word, He would Preserve it. (As the Bible says, "Heaven and earth will pass away by my Word will endure forever." and, Jesus said, "I will build my church and the gates of hell has not prevailed against it.")
6. Jesus also said to try His word to Know it. So for the last 30 years I have done that. The fruit has been peace, joy, hope, and a growing graciousness. (In Mormonism, for example, during ten years I experienced no spiritual growth at all.
7. The Bible presents a clear, consistent, rational, and meaningful Gospel. Eastern religions, for example, are self-described as irrational. Christianity builds orphanages and Islam creates suicide bombers. Mormonism created people who are robotic students of law but who exhibit little genuine godly fruit. See my Statistics pages at: )
Having said all that, obviously no one will ever be able to prove either the existence of God or the correctness of the Gospel to the human mind. So, there is an element of "testimony" (which we call faith). My faith rests IMHO on the best foundations available to mankind. However, my opinion and four dollars will buy a Starbuck's.