There has always been a whirlwind of confusion that surrounds the commandment, "not to take the Name of the Lord in vain."
The Jews interpreted it to mean "don't speak the Name." Christians believe it refers to profane or irreverent use of His Name. Both are wrong.
God commands us not to take His Name in vain because He wants us to use it to get results. He wants us to use His Name as a power of attorney. He wants us to use His Name as a tool to cause His will and His promises to come to pass.