For an explanation of Jehovah/YHWH see also: God? What’s in a Name.
This altar was built after Gideon had his famous call to be a judge in Israel. Gideon was not sure of this “call” and told the Angel of the Lord that he was the smallest in his family and was not fit to deliver the people from the Midianite and the Amalekites.[Judg. 6]
After their conversation, Gideon prepares some meat and unleavened bread which he sets on a rock before the Angel of the Lord, who then touches it with His staff and it is consumed in fire. This causes Gideon to be a little fearful for he realizes that he has seen God. The Lord reassured him that there is peace between them.
23 But the LORD said to him, “Peace be to you; do not fear, you shall not die.” 24 Then Gideon built an altar there to the LORD, and called it, The LORD is peace. To this day it still stands at Ophrah, which belongs to the Abiezrites.
With the courage that being the friend of God brings Gideon, he attacks the nearby altar of Baal and builds a new altar to the Lord and offers sacrifices to the One True God. His neighbors want to kill him for this offense. Gideon’s father asks these people if they are defending Baal, and suggest that if Baal is such a powerful god he can defend himself.
With the peace/friendship of God, Gideon goes on to be one of the most successful battle judges in the history of Israel. So to we can have this same peace.
Therefore, since we are justified by faith, we have peace with God through our Lord Jesus Christ. Rom. 5:1
When there is peace with God there is often conflict with man. For the natural man is at peace with Satan whether they know it or not. They love the altars of Baal, and find ways to bring them into the true congregation.
It is only in obedience that we achieve peace with God.
17 I appeal to you, brethren, to take note of those who create dissensions and difficulties, in opposition to the doctrine which you have been taught; avoid them. 18 For such persons do not serve our Lord Christ, but their own appetites, and by fair and flattering words they deceive the hearts of the simple-minded. 19 For while your obedience is known to all, so that I rejoice over you, I would have you wise as to what is good and guileless as to what is evil; 20 then the God of peace will soon crush Satan under your feet. The grace of our Lord Jesus Christ be with you. Rom. 16:17-20