Kadame I salute you for a very well reasoned response, not to mention your wholesome understanding of JW and SDA, the church I belong to. For a complete answer to RV Item, we need to come to a common understanding of what a cult is. Historically, the label has been used to refer to "a system of religious or spiritual beliefs, especially an informal and transient belief system regarded by others as misguided, unorthodox, extremist, or false, and directed by a charismatic, authoritarian leader".
The key words in the definition is "regarded by others". Which means if others are misguided then there is really no basis for making the claim. In simple English, the word cult is extremely prejudiced and subjective. In theological practice, it is derogatory. It is as subjective as the word mainstream.
The use of labels like cult may look innocent today, but in history, beliefs systems contrary to the Universal Church were called heretical and led to the Inquisition in various countries. The numbers of those who died or were made to convert are mind-boggling. Calling someone a heretic was not dissimilar to shouting Mwizi! in the middle of Gikomba - a sure death sentence, many times instant. At best, one would be excommunicated.
http://en.wikipedia.org/wiki/InquisitionIf one were to use the rest of the definition (misguided, unorthodox, extremist, or false) then all churches qualify in some way. Charismatic Pentecostals are misguided in many ways (prosperity gospel and over-emphasis on 'miracles' being two factors), so they qualify as a cult. All churches that worship on Sunday can be regarded as cultic.
http://www.romeschallenge.com/Even Kadame's Catholic church may be regarded by others as a cult. The Catholic church may evens out with JWs given that they have some unorthodox beliefs (worship of Mary, adoration of saints, infant baptism, purgatory...) are led by a charismatic, authoritarian leader. They even have their own version of the Ten Commandments and the Apocrypha (books not found in other Bibles).
Eventually, one needs not be scared by labels like cult or mainstream. Follow what the bible tells you and if that fits with your church, let it be. If your church does not follow the Bible, you are in a cult even if the church is mainstream.
I have seen Vooke's attack on SDA and Ellen G. White. Completely unwarranted and unsubstantiated. It seems he was foaming in the mouth as he typed those words.
3. Like Bittertruth stated, cults occasionally dab in the prophetic with devastating results.
SDAs or Ellen G White once infamously predicted 1844 to be end of the Age. When it failed, the stupid prick could not bring herself to apologizing, she REVISED her prophecy. 1844 was now the year Christ started atonement or when He entered the Holy of Holies in heaven from the outer court!
A simple search on Wikipedia could have saved Vooke the embarrassment.
http://en.wikipedia.org/wiki/Great_Disappointment