The Measuring Tool
When a carpenter needs to measure something, he uses his tape measure; it is the only source of 100% truth. He cannot use his finger, his elbow to finger-tip length, the width of his hand, or just “eyeball it”. If he did, the measure would not be accurate.
Likewise, if he were to measure it and thinks, “O, that just can't be right; I know by experience that it is longer/shorter than that,” then he should not be surprised that the measure is wrong—the part does not fit.
So today the only source of 100% truth is the Bible, but people want to add to it or marginalize it. The believe the whole Bible is true, but they think, “O, that just can't be right; I know by experience that it is _________.” They may depend on a certain teacher, book, feeling, dream, vision, voice, or something else as the final authority. All that does is change/wrest/deny the absolute truth.
I have heard people say they check every dream, vision, feeling, experience, book, teacher, etc with the Bible, but do they really take the time? Do they write down this feeling, experience, dream, vision, etc and actually check it out? I don't think so.
The measuring tape is the source of 100% truth in measuring, so the Bible is the only source of 100% truth for Christianity.
PS: The measuring tool may be electronic, mechanical, or sound but it still measures by the same standard—an eighth of inch is still an eighth of an inch, and a millimeter is still a millimeter.
The Bible says:
Deuteronomy 25:14-16 ISV (14) Don't have different measuring devices in your house—one large and one small. (15) You must have honest weights and measuring devices, so you may live long in the land that the LORD your God is about to give you, (16) for anyone who does these things—anyone who deals dishonestly—is detestable to the LORD your God."
2 Timothy 3:16-17 ISV All Scripture is God-breathed and is useful for teaching, for reproof, for correction, and for training in righteousness, (17) so that the man of God may be complete, thoroughly equipped for every good action.