Do they not err that devise evil? but mercy and truth shall be to them that devise good.
We need a conviction of truth because we cannot convince others of something we aren’t convinced of ourselves.
 As he spake these words, many believed on him.  Then said Jesus to those Jews which believed on him, If ye continue in my word, then are ye my disciples indeed;  And ye shall know the truth, and the truth shall make you free.  They answered him, We be Abraham’s seed, and were never in bondage to any man: how sayest thou, Ye shall be made free?  Jesus answered them, Verily, verily, I say unto you, Whosoever committeth sin is the servant of sin.  And the servant abideth not in the house for ever: but the Son abideth ever.  If the Son therefore shall make you free, ye shall be free indeed.  Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.  And because I tell you the truth, ye believe me not.  Which of you convinceth me of sin? And if I say the truth, why do ye not believe me?  He that is of God heareth God’s words: ye therefore hear them not, because ye are not of God.
Truth is our standard of discernment.
 Jesus answered, My kingdom is not of this world: if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews: but now is my kingdom not from hence.  Pilate therefore said unto him, Art thou a king then? Jesus answered, Thou sayest that I am a king. To this end was I born, and for this cause came I into the world, that I should bear witness unto the truth. Every one that is of the truth heareth my voice.
God’s Word is the standard of truth.
 Pilate saith unto him, What is truth? And when he had said this, he went out again unto the Jews, and saith unto them, I find in him no fault at all .
 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.  And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;  Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
 Sanctify them through thy truth: thy word is truth.
 And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent.
 Then went the Pharisees, and took counsel how they might entangle him in his talk.  And they sent out unto him their disciples with the Herodians, saying, Master, we know that thou art true, and teachest the way of God in truth, neither carest thou for any man : for thou regardest not the person of men.
God’s Word is the source of truth and it is available to all.
 The preacher sought to find out acceptable words: and that which was written was upright, even words of truth.
 For God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil.
 For the grave cannot praise thee, death can not celebrate thee: they that go down into the pit cannot hope for thy truth.  The living, the living, he shall praise thee, as I do this day: the father to the children shall make known thy truth.
 I have chosen the way of truth: thy judgments have I laid before me .  Thou art near, O Lord ; and all thy commandments are truth.