Ephesians 4:25 says "Therefore each of you must put off falsehood and speak truthfully to your neighbor, for we are all members of one body."
Telling the truth can be hard. In times of trouble, our instinct is to lie. A mother might ask who ate the last cookie, and her child instinctively knows to deny involvement. The child may even blame a sibling.
As believers, we must live in a way that only allows for truth. In his letter to Titus, Paul uses the word "blameless" (Titus 1:6, NIV) to describe who should be an elder, or as the English Standard Version translates the word "above reproach." I've always loved that translation. Yes, being blameless is good. However, to live your life in a way that people can't even accuse you of wrong doing, that is being above reproach. And that is powerful.