O, God, who will dwell in Your tabernacle, who will rest on Your holy mountain? ... One who speaks the truth in his heart ... who swears to his own hurt but will not retract (Psalms 15:1-4).
In their mind's eye, people believe that they are acting as truthfully as possible. We all know, however, how easily we can deceive ourselves. Since truth may be elusive, how then can we know that we have the truth?
There is a useful litmus test. We can know that we have the truth when we have the courage to feel the pain of accepting the truth. People lie because they think the lie will be less painful or costly for them than the truth.
People often fail to grow because they are reluctant to face the painful truth that they have done wrong. We have an innate tendency to avoid pain, and therefore we are apt to conjure up rationalizations that justify our behavior. These rationalizations are nothing but lies ― sometimes clever and convincing, but lies nonetheless. Facing the truth and accepting the pain that comes with it requires courage.
People who "speak the truth in their heart," says the Psalmist, do not retract their word even if it is to their own hurt. On the other hand, those who constantly seek to change everything to conform to their maximum comfort are only lying to themselves.