The only way we know about Peter de Bruys is through his enemies. We have no books written by Peter. No admirers ever wrote his history. All we have are Catholic writers who wrote against him since he challenged the Roman Catholic church. One such source is Peter the Venerable--the abbot of Cluny. The abbot of Cluny wrote a book that was directly against the teaching and followers of Peter de Bruys. This book is the main source of our information about this preacher.
We know he was a priest for a time. He came on the scene in southern France around the year 1105. Although we are not certain even of the date. He preached for some 20 years in the south of France, bringing about a revival and the emptying of Catholic churches of worshippers. Then around the year 1126, a mob laid hands on Peter and he was burned to death.
Later on a man named Henry of Lausanne joined in the work that Peter had started. His preaching against sin lead many people to repentance and it also stirred up the clergy whose sins he denounced. Henry was arrested and then imprisoned. We don't know what happened to him there. Those who held to the teachings of Henry and Peter de Bruys were called Petrobrusians. At the synod of Toulouse in 1119, the Petrobrusians were formally condemned as heretics. This group eventually scattered and disappeared; perhaps due to persecution.
We know more about what these men preached and taught because this is what their enemies wrote against. First, we know that they rejected infant baptism and practiced believers' baptism only. As you can see, believer's baptism only didn't start with the Anabaptist. Many others realized that infant baptism was unscriptural years before the reformation. Second, they didn't believe that church buildings, altars or crosses were holy or sacred. God could be worshiped wherever a person was. These people understood that God is to be primarily worshiped by our hearts rather than by outward traditions and mere form. Third, they rejected the catholic mass as unbiblical. Fourth, they taught that we can't do anything on behalf of the dead.They rejected purgatory as false. Fifth, they believed that "piety is essential to a legitimate priesthood." Serious sin in a leader of the church disqualified them for that position, as is taught in 1 Timothy 3.Sixth, they taught that priests were allowed to marry. Lastly, they believed that the church is made up of those who have been redeemed and born again by God. This was opposed to the Catholic church which taught the church was all those who are in a given locality, that is a parish system. This is what we know they taught from what their enemies wrote against them.
When you examine the teachings of Peter de Bruys, you should see that there is not much difference between them and what you see in many solid biblical churches today. 400 years before the Reformation, we read of a man who stood for the truth of God's word. He was evidently a man who knew and studied his Bible well. He must have been a man of courage to preach against the mighty Roman Catholic church. In the end he gave his life for his Lord. Our record of this man is incomplete. I would love to know more. But much remains unknown to us. However, God knows all about Peter de Bruys. He remembers what he did even if many or all forget him. This is true for us. History will likely forget us. But the Lord Jesus never forgets His people or their service for Him. He will reward us in His good time. Knowing this let us press on to holiness and serve our King.
Phillip Schaff's History of the Christian Church Vol 5 pages 482-485