He claimed that an angel had conferred miraculous powers on him at birth, and that another had brought him relics of great sanctity from all parts of the earth.
According to St Boniface, he erected crucifixes at fields and springs and claimed to have received a letter that Jesus Christ had given from heaven to Jerusalem, which Aldebert used in his own preachings.
He used mystic prayers of his own composition to call on angels who were not accepted by church canon (Uriel, Raguel, Tubuel, Adinus, Tubuas, Sabaoc and Simiel), and who his detractors alleged were demons (some of these names had gnostic connections).
St. Boniface wrote to Rome asking for the Pope to help him "lead back the Franks and Gauls to the right path",[2] claiming that Aldebert had seduced the multitudes.
A German synod the following year, presided over by Boniface and Carloman, excommunicated him along with an Irish preacher named Clement and many others.