It is clear that you may call yourself "mainstream Christian" however that is not what Jesus or any other prophet was in their day!  I suppose if anyone has a web site these days, they are considered an expert on the matter regardless of authenticity or knowledge!  Lets look at what you've presented:

"God never tells us to pray about what is true. When we want to know how tall a wall is, we don't pray about it...we get something that we know is true (a ruler) and compare it to the wall. The Bible, God's word, is true. That is our measuring stick for truth"

Which bible was that “ruler” oh, by the way is that English(American) or metric(European) scale?  (they are different!)

Luther Bible 1545

21st Century King James Version

American Standard Version

Amplified Bible

Contemporary English Version

Darby Translation

Douay-Rheims 1899 American Edition.

English Standard Version

Holman Christian Standard Bible

King James Version

New American Standard Bible

New International Reader's Version

New International Version

New International Version - UK

New King James Version

New Life Version

New Living Translation

The Message

Today's New International Version

Worldwide English (New Testament)

Wycliffe New Testament

Young's Literal Translation

In any instance your "bible" contains many things that have been changed, voted upon, or deleted from Canon

Where is the Shepherd of Hermas, Apocalypse of Peter, Epistle of Barnabas, or the Epistle of Clement? (Just to name a few)  Here is a list of good books (unbiased) to further your education if wished:

The Canon of Scripture by Frederick Fyvie Bruce

The Canon of the New Testament: Its Origin, Development, and Significance by Bruce M. Metzger

What is funny, when you actually think about the statement, It implies that there is no truth without the “bible”.  Since it took approx 400 years to compile most of what is found in the western biblical cannon, it goes to say that there was no “measuring stick for truth” for all of earth’s history until approx 400AD. Wow! Not even Jesus Christ’s life, ministry or actions (what he said and did in HIS TIME) was considered truth until the bible stated it was so!

"Feelings are unreliable because they are subjective, easy to produce, and are not meant to discover facts but to tell us how we feel about facts."

Ya, much like RAIN (water falling from the sky) it is also subjective, easy to produce, and is not meant to discover facts but to move water around the earth.  And I have found that no matter what I feel about rain, I KNOW that when I stand in it, I get wet! (Do you have a different experience?)  The same can be said about the Holy Ghost, No matter how I “feel” about it, I know that it exists (much like rain) and when I choose to follow the “Still small voice” I draw closer to GOD!  It is also interesting “FACT” that this is the very way that the bible was assembled and Canonized. 

"While we cannot judge another person's motives we can and must judge what a person does or says."

Pause…  Sorry had to stop to make sure I really read this correctly is this for real???  It must be a joke right?  You just put in to see if I was really reading your response right???  If not, I truly don’t know what to say, because I wouldn’t know where to start!   To me it is like saying the earth is flat.  While it might have been a good interpretation to try and understand things based upon our limited knowledge at one time, it is in fact Just WRONG!

Final thoughts—I would continue to learn more about your own religion (mainstream Christianity), its history, documents, and beliefs.  Get to know the good and bad rather than just quote others opinions.  I consider myself a Christian and have a friend who shoots HUGE holes through religion, Christianity, the bible, its history etc…  I thank God for him everyday, because I would never have truly studied BOTH sides of religion, Christianity, Mormonism, the bible, etc without his influence! (You see he is not concerned that I may be a Mormon, he is concerned how I am swayed to even think that religion or Christianity are even viable solutions to help anyone live life.)  What would you say to him?  Would he still be your friend?

I believe that religion was not created to defend, convert, or condemn people, but rather to bless peoples lives regardless of belief.