You address your question to Jehovah's Witnesses. Surely you are aware that many professed Christians flatly reject the doctrine of the Trinity. Not a few of them post right here on Yahoo.
Why did Jesus not "correct him for making either a false assumption or a blasphemous statement?" Jesus did not always correct the false assumptions of his apostles. Examples embedded in scripture. And I do not see any basis for suggesting that Thomas was being blasphemous.
I think you mentioned something about researching the meaning of the Trinity doctrine and not getting it from the Governing Body. I agree wholeheartedly. The doctrine comes to us from the Roman Catholic church (which as you know predates the Protestant church by centuries). The trinity is based on the Catholic Athanasian Creed. Submitted herewith for your perusal is the definition in its entirety:
"Whosoever will be saved, before all things it is necessary that he hold the Catholic Faith. Which Faith except everyone do keep whole and undefiled, without doubt he shall perish everlastingly. And the Catholic Faith is this, that we worship one God in Trinity and Trinity in Unity. Neither confounding the Persons, nor dividing the Substance. For there is one Person of the Father, another of the Son, and another of the Holy Ghost. But the Godhead of the Father, of the Son and of the Holy Ghost is all One, the Glory Equal, the Majesty Co-Eternal. Such as the Father is, such is the Son, and such is the Holy Ghost. The Father Uncreate, the Son Uncreate, and the Holy Ghost Uncreate. The Father Incomprehensible, the Son Incomprehensible, and the Holy Ghost Incomprehensible. THE FATHER ETERNAL, THE SON ETERNAL, AND THE HOLY GHOST ETERNAL and yet they are not Three Eternals but One Eternal. As also there are not Three Uncreated, nor Three Incomprehensibles, but One Uncreated, and One Uncomprehensible. So likewise THE FATHER IS ALMIGHTY, THE SON ALMIGHTY, AND THE HOLY GHOST ALMIGHTY. And yet they are not Three Almighties but One Almighty.
So the Father is God, the Son is God, and the Holy Ghost is God. And yet they are not Three Gods, but One God. So likewise the Father is Lord, the Son Lord, and the Holy Ghost Lord. And yet not Three Lords but One Lord. For, like as WE ARE COMPELLED BY THE CHRISTIAN VERITY TO ACKNOWLEDGE EVERY PERSON BY HIMSELF TO BE GOD and Lord, so are we forbidden by the Catholic Religion to say, there be Three Gods or Three Lords. The Father is made of none, neither created, nor begotten. The Son is of the Father alone; not made, nor created, but begotten. The Holy Ghost is of the Father, and of the Son neither made, nor created, nor begotten, but proceeding.
So there is One Father, not Three Fathers; one Son, not Three Sons; One Holy Ghost, not Three Holy Ghosts. And in this Trinity NONE IS AFORE OR AFTER OTHER, NONE IS GREATER OR LESS THAN ANOTHER, BUT THE WHOLE THREE PERSONS ARE CO-ETERNAL TOGETHER, AND CO-EQUAL. So that in all things, as is aforesaid, the Unity is Trinity, and the Trinity is Unity is to be worshipped. He therefore that will be saved, must thus think of the Trinity.
Furthermore, it is necessary to everlasting Salvation, that he also believe rightly the Incarnation of our Lord Jesus Christ. For the right Faith is, that we believe and confess, that our Lord Jesus Christ, the Son of God, is God and Man.
God, of the substance of the Father, begotten before the worlds; and Man, of the substance of His mother, born into the world. Perfect God and Perfect Man, of a reasonable Soul and human Flesh subsisting. Equal to the Father as touching His Godhead, and inferior to the Father as touching His Manhood. Who, although He be God and Man, yet He is not two, but One Christ. One, not by conversion of the Godhead into Flesh, but by taking of the Manhood into God. One altogether, not by confusion of substance, but by Unity of Person. For as the reasonable soul and flesh is one Man, so God and Man is one Christ. Who suffered for our salvation, descended into Hell, rose again the third day from the dead. He ascended into Heaven, He sitteth on the right hand of the Father, God Almighty, from whence he shall come to judge the quick and the dead. At whose coming all men shall rise again with their bodies, and shall give account for their own works. And they that have done good shall go into life everlasting, and they that have done evil into everlasting fire. This is the Catholic Faith, which except a man believe faithfully and firmly, he cannot be saved." (Caps mine) End of definition.
This doctrine violates the Scriptures in their entirety; particularly the sections in all caps. What do other professed Christians say about the Trinity?
The current mainstream teaching in Christianity is that God is a coequal, coeternal, one-substance trinity, and that Jesus Christ is God. This doctrine is considered by many as the cornerstone of Christianity, but where did this doctrine come from? The historical record is overwhelming that the church of the first three centuries did not worship God as a coequal, coeternal, consubstantial, one-substance three in one mysterious godhead. The early church worshipped one God and believed in a subordinate Son. The trinity originated with Babylon, and was passed on to most of the world's religions."
www.christadelphia.org
"In all Scripture, there is nothing to justify this absurd and self-contradictory mizmaze. While truly we can never hope with mortal minds to comprehend God, still the revelations He gives of Himself, and of His Son, and of His Holy Spirit - His power and presence which fills all immensity and works His will - is clear and simple and reasonable and a tremendously satisfying relief from the befuddled speculations as quoted above. The doctrine of the "Trinity" is nowhere found in the Bible. "
G.V. "Rene" Growcott (www.antipas.org)
. . . the history of the trinity doctrine is open knowledge. The true church never accepted the idea, and even the false church did not embrace it until three centuries after Christ! Even then, it was only accepted as a political concession to the Roman emperor, Constantine. Add these facts to its absence in the Scripture, and it is no wonder the Catholics and Protestants call it a mystery!"
"Fact is, it's rather easy to expose the deception of the trinity."
"The trick used by trinitarians to try and prove three Gods are three persons, is their use of segmentalism. They will take segments of Scripture, segments of a text, segments of an incident, out of the context of the whole Bible, and try to make them say what the entire Bible refutes."
Pastor G. Reckhart
"The Early Church of the Bible knew nothing of a Trinity Doctrine. The very term "Trinity" or the teaching of it as a Christian doctrine did not start until 180 A.D. This is almost 150 years after the Church, under the new covenant, started in A.D. 33 on the day of Pentecost. One can search the Acts of the Apostles in the Bible which is the true History of the early Church thoroughly and not find any of the Apostles teaching the Trinity.
Thunder Ministries. Com
Yet how many verses clearly contradict the trinitarian view? There are hundreds. This is not a matter of a few verses clarifying or modifying a scriptural precept. Rather, it is a matter of hundreds of verses contradicting less than half a dozen. The burning question that needs to be answered is why do people cling to the half dozen or so, and reject the hundreds?"
www.jesusfamilies.org
"One reason I reject the doctrine of the Trinity is that there is a huge constellation of false doctrine orbiting it. It was after this debate that I decided to make an actual list of the different false doctrines that have been given birth because of the Trinity doctrine."
Kenneth James Solheim Th.B.
"It is amazing to me that many Trinitarians believe that their cherished belief was one believed upon by all Christians since Jesus day. The truth, however, is that the trinity was not believed upon by all Christians even as late as the Counsel of Nicene at 325 A.D."
Kenneth James Solheim Th.B.
"The doctrine of the "Holy Trinity" considered by many to be essential to one's very salvation, is not found in Christianity until at least three hundred years after the crucifixion of Jesus Christ. Even more shocking is the fact that the concept of a triune godhead likely comes from the traditions of paganism!"
www.angelfire.com
Hannah J Paul