The "Moulders of Opinion" generally speaking are: editors, publicists, politicians, and some preachers. As a rule these opinion fixers are not speaking to enlighten the masses, but rather to make us act, feel and vote with them in propagating their "cause" or party. Opinion can never be more than a provisional conviction to be held only and until weightier testimony is produced to lead to the truth on any proposition. In religious matters opinion, if indulged at all, should be held strictly as private property and never put forth as a "doctrine."
"Opinion, in Latin — opinio from opinor, and Greekopinoeo — to think or judge, is the work of the head. "Sentiment" — from sentio, Latin — to feel — is the work of the heart. Opinions are formed on speculative matters; they are the result of reading, experience and reflection; Sentiments are entertained on matters of practice... Opinions are more liable to error than sentiments. Opinion springs from imagination, and in all cases it is but an inference or a deduction which falls far short of certain knowledge: Opinions therefore, as individual opinions are mostly false... difference of opinion among men, on the most important questions of life is sufficient evidence that the mind of man is very easily led astray on matters of opinion" — "Opinionated or Opinionative" — A fondness for one's opinion bespeaks the opinionated man...the pinionated man is not only fond of his own opinion, but is full of his opinion; he has an opinion on every thing, which is the best possible opinion, and is therefore delivered freely to every one that they may profit in forming their own opinions." (Crabb's English Synonyms, pp. 643, 644) In talking with people on religious subjects, how often do you hear this expression: "I believe thus and so"? — when in fact they mean: it's my opinion, thus confusing "belie`" or "faith" with opinion, and from people who ought to know better! In the absence of testimony it is impossible to believe. "Faith comes by hearing" testimony. (Romans 10) In matters of Christian faith opinion is necessarily excluded, that should and does end all controversy, in so far as God is concerned.
If as our authority on opinion declares (and who will question the correctness of his word analysis?) "opinion springs from imagination," let's notice what Paul says about the "progenitor" of Opinion. Romans 1:21...
"When they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened: professing themselves to be wise they became fools." Can't you see the "chain reaction"? Following imaginations (opinion) — "sentiment" work of the heart — became darkened and corrupted. Opinion not only corrupts the reasoning faculties but also the heart.
Before Paul was converted, he was quite an opinionated man — for what was the traditions of the Jews but mummified opinions of men? Paul's former course was: "verily I thought within myself I ought to do many things contrary to the name of Jesus of Nazareth, which thing I also did in Jerusalem." (Acts 26) But God showed Paul that — "My thoughts are not your thoughts — neither are your ways my ways." (Isaiah 55:8) Later we hear Paul say — "For I determined not to know anything among you, save Jesus Christ and Him crucified." (1 Cor. 2:2) Again...the weapons of our warfare are not carnal, but mighty through God is pulling down of strongholds, casting down imaginations and every thing that exhalteth itself against the knowledge of God." (2 Corinthians 10:4, 5)
Paul instructs Titus how to act towards "an heretic) (hairetikos) "Opinionative person." (Young's Concordance p. 477) "A man that is an heretic, after the first and second admonition reject: knowing that he that is such is subverted (see dictionary) and sinneth, being condemned of himself." (Titus 3:10,11)
We have another word that is similar if not quite identical in meaning, but is applied to a collection of individuals rather than to one man. However the "heretic" is the leader or the "spark plug" of the defection and is the occasion, if not the cause of the party.
"Heresy — from Greek — hairesis — "a choice, signifies an opinion adopted by individual choice...as all division supposes error either on one side or both. The words heterodoxy and heresy are applied only to human opinions and strictly in a sense of false opinion formed in distinction from that which is better founded; but the former respects any opinion important or otherwise, the latter refers only to matters of importance: the heresy is therefore a fundamental error." (Crabb's Synonyms, p. 510)
1 Corinthians 11:19, "For there must be also heresies among you that they which are approved may be made manifest among you." 2 Peter 2:1-3, "But there were false prophets among the people even as there shall be false teachers among you, who shall privily bring in damnable heresies, even denying the. Lord that bought them, and bring upon themselves swift destruction, and many shall follow their pernicious ways: by reason of whom the way of truth shall be evil spoken of, and through covetousness shall they with feigned words make merchandise of you...their damnation slumbereth not." - The real measuring rod to test religious ideas is: Divine Revelation. "If any man speak let him speak as the oracles of God." (1 Peter 4:11) Always look beyond the "teacher's" exposition of ideas for his motive, for no man does anything without a "motive" — if his teaching conflicts with revelation — he is either ignorant of his subject, or a wilful perverter of the true Way. "There is sure to be some 'doctor' at the head of a schism." (Cardinal Bellarmine)
Peter says that some teachers are out "to make merchandise of you." Personally I think Peter knew what he was talking about. And old Brother John said, "Believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world." (1 John 4:1)