You would think that there should be a logical way of discussing these things, but there surely is not, if there were thousands would leave.
Even when you present them with hard evidence they still seam to have a closed mind.
Even when scripture is used ( Isaiah 1 v18 come now you people and let us put matters straight between us says Jehovah ) even then, there is no guarantee that this approach will work.
In the end it has to come from the person himself or herself.
KT