The Lord here commissions his servants to do all they can to establish peace on earth. Treaties and agreements and armistices are to be applauded, but the only ultimate peace in the world will come through the power of Jesus Christ. Jesus Christ is the Prince of Peace.
His message, the gospel of salvation is a message of peace. He brings peace- but not as the world does (see John 14:27)- to those who will receive him, come unto him, obey him, follow him, and submit to him. He remits sin, and that brings peace.
He steadies the troubled soul, which brings peace. He comforts the bereaved, which brings peace. He offers heavenly perspective, which brings peace. His Spirit teaches the “peaceable things of the kingdom” (D&C 39:6; see also Moses 6:61). In addition, those whom he calls and sends forth in his name are peacemakers; these are they which bear glad tidings, which publish peace, even the message that God reigns (see Mosiah 15:13-18).
“The peace the gospel brings,” Elder Dallin H. Oaks has taught “is not just the absence of war. It is the opposite of war. Gospel peace is the opposite of any conflict, armed or unarmed. It is the opposite of national or ethnic hostilities of civil or family strife … . By preaching righteousness, our missionaries seek to treat the causes of war.
They preach repentance from personal corruption, greed, and oppression because only by individual reformation can we overcome corruption and oppression by groups or nations. By inviting all to repent and come unto Christ, our missionaries are working for peace in this world by changing the hearts and behavior of individual men and women.” (CR, April 1990, pp. 91, 94, italics in original.)