Unfortunately, we Catholics have no materials the JWs will ever read… until they have already decided to leave the JW religion.
Walking through Pillar of Fire, Pillar of Faith might help if you know your faith and this booklet very well.
Know this, the JW religion uses very strong rhetorical tools to distract, delete, badger by repetition, reframe, etc., constantly returning the discussion only to topics with which they feel familiar. So, unless you have strong rhetorical skills of your own, to control the frame of the conversation, you have one brief chance to plant a seed of doubt in the JW evangelizers.
The simple, but powerful, “seed of doubt” I have used focuses on their very name for God, “Jehovah,” which no other religion uses. In fact, all authorized Christian Bibles have corrected this error in their most recent editions.
Simply ask the JW(s) from which language the name Jehovah originates.
Most will answer Hebrew (wrong). Some might venture the answer Aramaic (wrong) or Greek (wrong). The orignal Scripture texts used all of these (Scripture used “Koine” or people’s common Greek, not Classical Greek). JWs claim their “translators” used the original texts from which to translate their “New World Translation.” This issue has come up in several court cases. The “translators,” whom the JWs do not name under the pretense of humility, had their names revealed in official court records by a former JW who participated in the “translation.” On further investigation, only one of the “translators” had any education beyond high school. That individual had two years of college, which included two years of Classical (not Koine) Greek. NONE of the “translators” had any education in any of the Biblical languages, making their ability to translate from the original Scriptures impossible (or miraculous!). The correct answer about the origin of the name Jehovah tracks back to a mis-transliteration by a Catholic monk of the Hebrew scriptures from the Masoretic Jews. The Jewish Masorites wrote a translation of the Hebrew (Old Testament) scirptures somewhere between 600 and 900 AD (or, if you prefer, CE). Interpreting the Second Comandment (Do not use the Name of the Lord in vain) to mean they should NEVER speak the Name of God, as given to Moses (“I AM” or “I AM WHO I AM,” written in Hebrew as IHWH, since ancient Hebrew did not use or even have vowels in its written language. The IHWH may appear under the term “Tetragrammaton,” which simply means four-letter-term in Greek). So the Masorites instructed the reader, at every instance of “IHWH,” by inserting superscript vowels between each of the four letters. They used the vowels for either “elohim”(Lord) or “adonai,”(God) depending on the context of the scripture. Therefore, selectively choosing the option for “adonai,” we get “I-a-H-o-W-a-H.” Through mis-transliteration over the years, this became Jehovah, a no-language mistake. (An example of a similar mistransliteration might arise from taking the newspaper name for former President John F. Kennedy, “JFK,” and inserting the vowels for “Kennedy,” to instruct the reader to say “Kennedy” when reading “JFK,” yielding the mistransliteration “J-e-F-e-K” or “J-e-F-e-K-y.”) All reputable Biblical scholars have since realized this error and corrected the translations of their most recent editions.
So far I have not met a JW with a reasonable or plausible reply to the simple question, “From which language does the name Jehovah originate?” When you explain the origin and challenge them to “look it up,” they will, hopefully, begin to question other things the JW leadership has told them to take, repetitively, word-for-word, without questioning, and from no other source except the Watchtower publications or official leadership. This last sentence includes numerous practices of organizations which practice mind control in the rhetorical methodology. (Refrain from using the term “cult,” since this has positive as well as negative connotations. The Catholic Church itself uses the term cult in reference to the followings of the practices of particular saints.)
Jason Evert’s fine and brief book, “How to Answer Jehovah’s Witnesses,” covers this and many related topics very well.