Hi,
For me is not a matter of one text. For me is something similar of what Jesus replied to que question of Mat 24:3, "... the sign of your presence", and then he gave us a collection of events. For me the collection of events that probe me that the WT didn't have the truth were:
1. The UN affair.
2. The replied that the WT gave us about his relationship with the UN. For me a complete lie, at least all the elders that signed this relationship must be removed for lack of sound of mind.
3. Then my research about blood. There are any evidence in the bible to forbide the blood, but not the fractions of the blood, you could understand as a complete forbide, but not as they actually taught.
4. My last understanding that there was not a Goberning Body in the first century. If you read again, Galatas, Act 15 and Act 21:20-24, you will understand that they were two kinds of christian teachings in the firsts century, the two of them with at least some degree of Holy Spirit aproval. Joseph Malik write an excelent chapter in his book Beyend Jehovah witness about this texts.
5. And all the other stuff that I learned, specially about the letter to Hitler in 1933, published in the yearbook of 1934, the aluminun stuff and many other more, like the endorsement of the book Womans and Angels ...
Many elders will replied, but to where can we go, but the bible ask: to whom can we go. Also in this text the WT lies to us. They put themselves in the place of Jesus Christ, maybe that is the reason because you will hear a lot of Jehovah and the faithfull slave in the Kingdom Hall, but so few about Jesus Christ.