Jehovah's Witnesses use the term "the Truth" to describe their faith because they/we BELIEVE that it is Bible based.
"Sanctify them by means of the truth; your word is truth." (Joh 17:17; compare Jas 1:18.)
In today's world, the term is often scorned because it represents finality, moral certainty and absolutism while all modern trends have pushed towards relativism, subjectivity and an acceptance and openness to accept minority and non-mainstream viewpoint. Scientific inquiry also generally rejects such notions as "truth" and prefers to deal instead in "probability" - always leaving open possibilities of exception and potential disconfirmation.
Simply put it is hard for us to accept that there is such a thing as truth or truths and any claims to have such seem arrogant.
It should be pointed out that in all fairness Jehovah's Witnesses, while generally feeling and claiming that their views and beliefs, etc. are "correct," they do not claim that their faith is the Truth in the absolute sense of the word. They understand that they only have partial knowledge, are prone to fault and error, and have an expectation of continued progress and change.
Again their use of the term is due not because they claim to be in possession of absolute Truth but because they are under the belief (mistakenly in some instances) that their faith is entirely "bible based" and therefore is the "Truth" since the Bible itself is viewed as the "Truth."
Further contributing to this view is the evident "falsehood" that can be easily discerned in other religions by contrast as they see it. When many are promoting what seem to be clearly lies or promoting what appear to be fantastic or self-delusional beliefs, their seemingly clear and logical viewpoint appears to be closer to absolute Truth - or as they see it, the "truth" that the Bible actually teaches.
PS: it appears that the term with reference to the association was used in this sense pretty much from the beginning....
OBJECT AND MANNER
OUR LORD’S RETURN
by C. T. RUSSELL
"Take heed to yourselves least at any time your hearts be overcharged
with.... the cares of this life; and so that day come upon you unawares."—
ROCHESTER, N. Y.
OFFICE OF HERALD OF THE MORNING
accomplished. He works " all things after the counsel of His will."
Not only is this true, but He has revealed his plan to us in " the Scriptures, which are able
to make us wise," and given us His Holy Spirit to enlighten our understanding, " that
the things that are freely given unto us of God." (1 Cor. 2:12.) Which things,
neither the world nor
Christians can see (v. 14); they are revealed by the
spirit in answer to diligent search. " If thou seekest after wisdom, and liftest up thy
voice for understanding, yea: if thou searchest for her as men search for silver; then shalt
thou find the knowledge of God." When He, the Spirit of Truth is come, He shall guide
you into all truth.
And this little article is from the first full issue of the ZWT:
ZION'S WATCH TOWER AND
HERALD OF CHRIST'S PRESENC
"Watchman, What of the Night?"
"The Morning Cometh."--Isa. 21:11.
VOL. I. PITTSBURGH, PA., JULY, 1879. NO. 1.
R8 : page 3
"WHAT IS TRUTH?"
This question is one which every sincere Christian should ask and seek to answer. We
should learn to love and value truth for its own sake; to respect and honor it by owning
and acknowledging it wherever we find it and by whomsoever presented. A truth
presented by Satan himself is just as true as a truth stated by God.
Perhaps no class of people are more apt to overlook this fact than the Christian. How
often do they in controversy overlook and ignore truth presented by their opponents.
This is particularly the case when arguing with an infidel. They feel at perfect liberty to
dispute everything he says on religious subjects. This is not the correct principle. Many
infidels are honest--as anxious to speak and believe the truth as are Christians--and if in
converse with them we ignore truths which they may advance, we not only fail to
convince them of our truths, but put an end to all hope of reaching them; for our failure
to admit the evident truth which they advance begets in them contempt for the one who
is not honest enough to admit one truth because he does not see how it can be reconciled
to another. Accept truth wherever you find it, no matter R9 : page 3 what it contradicts,
and rely for ability to afterwards harmonize it with others upon "The Spirit of truth,
which shall guide you into all truth," as Jesus promised.
Truth, like a modest little flower in the wilderness of life, is surrounded and almost
choked by the luxuriant growth of the weeds of error. If you would find it you must be
ever on the lookout. If you would see its beauty you must brush aside the weeds of error
and the brambles of bigotry. If you would possess it you must stoop to get it.
Be not content with one flower of truth. Had one been sufficient there would have been
no more. Gather ever, seek for more.
Weave them together as a garland --"Bind them on thee as a bride doeth." "Bind them
about thy neck; write them upon the table of thine heart: so shalt thou find favor and
good understanding in the sight of God and man." Prov. 3:3.
C. T. R.