In no area of human nature is our innate depravity and complete fallen-ness more apparent than in our inability to tell the truth. The legal oath to tell "The whole truth and nothing but the truth..." is a worthy goal, not only in court, but for the Christian, it is absolutely necessary in everyday life.
The problem, with me at least, is that it is not as easy as it sounds. Here's how it seems to work with me: When I hear something or when I witness some event; as the words, sounds and images enter into my mind through ears and eyes, I file them away, not necessarily as they were actually seen and heard, but I tend to color them with my own prejudices and preferences. Before they ever get into my memory banks, they are already tainted by my inherent fallen-ness. I have spun them before I even filed them.
Some people are willing to distort what they know to be the truth in the retelling. True Christians are not willing do that. However, for me (All of us?), the problem really is much deeper than that. Even if I am careful to try to tell things exactly as I heard or saw them, I am actually only telling what was put into my memory, not what really happened. I suppose this is why eye-witness testimonies often are very different, even when the witnesses saw or heard exactly the same thing.
Even at my very best, I am desperately in need of a merciful Savior. I am not sure if this "enemy" can be completely defeated in this life or not. However, I have identified him. Now I must guard against him.