Why Did Christ Say Baptize In The Name Of The Father, Son, And The Holy Ghost,

If There Are Not Three Personages (Matthew 28:19)?

In this passage (Matthew 28:19) we have a common phrase “in the name of” which means “by the authority” of someone or something (See: Understanding The Phrase “In the Name of..” and  In The Name of “Jesus”). Even today an officer of the law may call out to an escaping criminal: “Stop, in the name of the law.” He is giving notice to the criminal that he has the authority given him by law by which the criminal is to comply with his command to stop.