When we claim to be followers of His Son and bear His name and consistently commit sin, in a manner of speaking, we drag God down into the gutter with us. We must be careful in the verbal abuse of God's Name. This is usually the first thing we think about when we consider the third commandment. As we have discovered it is far more than this, but it also includes this idea. I doubt there is not a way we haven't found to misuse the names of God and Jesus in our everyday speech.
Jewish people consider the Name of God to be very holy.
Hebrew tradition holds that the actual Name of God was spoken only once a year by the high priest when he entered the Most Holy part of Temple on Yom Kippur, the holiest day of the year. We can misuse God's name by advocating that we have a special relationship with Him. Now I really can't question as to whether a person has heard from God or not, but if a person talks this way frequently, I begin to get uneasy. I get uneasy because it usually is tied with a personal agenda the individual has. After all, if we believe God told this person what to do, and we question what he says, we would actually be questioning God's authority.