"For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace." (Isaiah 9:6)
As I said in a previous post, it fascinates me that the title "The Prince of Peace" comes at the end of a list that appears to be written in ascending order of importance. Why is this?
"Peace" equals a lack of conflict, contention, struggle, strife, etc. Spiritual peace, therefore, is a condition - a calmness and stillness that can be shared with others and change their very existence. Being totally peaceful means acting always in harmony with how one should act - never being in conflict with the standards of what one should be. With this definition, one can be spiritually peaceful even while engaged in a battle - or clearing a temple with a whip - etc. It's a fine line - and it is dependent entirely on being in touch with the Holy Ghost. Being "at peace" is analogous to being "right with God" - of having all impediments to perfection removed and being able to access God's full grace with nothing standing in the way.
"The Prince of Peace" is a perfect description of the one who brings people into a unity with God that is known as "The Atonement" - the making of two otherwise incompatible entities one perfectly united whole. It is not "The mighty God" or even "The everlasting Father" who makes this incomprehensible result a reality; rather, it is "The Prince of Peace".