No one can argue with a testimony, it is not a debatable issue. It is there to be accepted or rejected. A testimony is fragile. It is as hard to hold as a moonbeam. It is something you have to recapture every day of your life.
Truth is it's own witness.
The possession of a sure testimony is the most valuable possession that one could have. It gives one knowledge, the hope and assurance that one, through obedience, can be a partaker of all the promised blessings. While this spiritual communication comes into the mind, it comes more as a feeling, an impression, than simply as a thought. Unless you have experienced it, it is very difficult to describe that delicate process. Elder Packer explained that the witness is not communicated through the intellect alone, however bright the intellect may be.