Menno Simons was born in 1496 in the Frisian village of Witmarsum and ordained a Roman Catholic priest around 1515 or 1516 in Utrecht, before becoming chaplain in his home region at Pingjum in 1524. Even as a young priest he privately doubted two of the church's central teachings, that the bread and wine of the Mass become the actual body and blood of Christ, and that an infant too young to believe could still be validly baptized. He kept these doubts to himself for years, unwilling to give up the security of his position.
The doubt became a crisis in 1535, when his brother Pieter was killed near Bolsward after taking part in a violent Anabaptist seizure of the Oldeklooster monastery, an episode that ended in a bloody royal reprisal. Menno later wrote that his brother's death, and his own sense that he had done nothing to warn him away from a false path, weighed on him until he could no longer stay silent. On 12 January 1536 he formally renounced Catholicism, and within the year he was baptized as an adult believer and ordained an Anabaptist minister by Obbe Philips.
What followed was twenty five years as a hunted preacher. An imperial price was placed on his head, and he moved constantly through the Low Countries and, later, northern Germany, gathering scattered and persecuted Anabaptist congregations into something more organized and lasting. He died on 31 January 1561 near Bad Oldesloe in Holstein, and was buried in his own garden rather than in consecrated ground that would have been denied him.