Explain to a Christian that the term Jehovah's Witness applied to members of the House of Jacob. Then say Jesus was the greatest one who came from the House of Jacob.
Next explain that your denomination has taken the name of the entire House of Jacob and they are just like the Methodists attempting to get back to what Jesus really said. Having put on a reasonably good show with the preaching work and sound moral values (on the face of it) boldly say, "if you can find anything better, you tell us and we will ALL come with you." Follow that with, "we know we've made mistakes but we are not like the Catholic Church. If we have anything wrong we will change it. We are simple men just doing our best."
This is called a confidence trick and it relies on trusting people not have the insight to ask the right questions to reveal the trick. It happens in other areas of life too.
One question that should be asked is - "WHEN will a false teaching be changed?" Answer - "next pancake Friday."
NOW you see through it. But who is going to be that suspicious that these apparently nice Christian people are pulling a fast one UNTIL you have got to know them? Also some of them are genuine, even if they have been misled. They were conned too.