Peter Waldo (/ˈwɔːldoʊ, ˈwɒl-/;[1] also Valdo, Valdes, Waldes; French: Pierre Vaudès, de Vaux; Latin: Petrus Waldus, Valdus;[2][3] c. 1140 – c. 1205) was the leader of the Waldensians, a Christian spiritual movement of the Middle Ages.

In his A History of the Vaudois Church (1859), Antoine Monastier quotes Bernard, Abbott of Foncald, writing at the end of the 12th century, that the Waldensians arose during the papacy of Lucius.

The region of Lombardy was a hotbed of religious reform movements at the time, many of which would be later deemed heresies by the Catholic Church.

[4] Other events, besides hearing of Saint Alexius, may have also contributed to Waldo's decision to take up poverty and preaching including a rejection of transubstantiation when it was considered a capital crime to do it,[citation needed] and the sudden and unexpected death of a friend during an evening meal.

[13][14] From this point onward he began living a radical Christian life, giving his property over to his wife, while the remainder of his belongings he distributed as alms to the poor.

At about this time, Waldo began to preach and teach publicly, based on his ideas of simplicity and poverty, notably that "No man can serve two masters, God and Mammon.

The Waldensian movement was characterized from the beginning by lay preaching, voluntary poverty, and strict adherence to the Bible.

They continued to gather followers and began proclaiming doctrines at odds with Catholicism - such as the right of all worthy members including women to preach the Scriptures without permission from Church authorities.

[4] The Waldensians developed a doctrine that forbids the use of weapons or of oaths, which led them to refuse any participation in Catholic rituals.

[23][24][25] Driven away from Lyon, Waldo and his followers settled in the high valleys of Piedmont, and in France, in the Luberon, as they continued in their pursuit of Christianity based on the New Testament.

The doctrine of the Poor of Lyons was again condemned by the Fourth Lateran Council in 1215, when they mentioned the group by name for the first time, and declared its principles to be heresy.