It is not about what people call truth, it is about what is Truth. This is why Faith is such an important part of being a Christian.
And as your quote from the bible details the truth is sharp! It hurts peoples feeling very often, that is why we often recoil from it. I just noticed that the word truth actually contains the letters for the word hurt...interesting in itself.
"I have not written to you because you know not the truth, but because you know it, and that no lie is of the truth."