Novatianism

Novatianism was a sect of the Early Christian Church that followed the Roman cleric Novatian (c.200-258 CE).
Novatian refused to accept the return of those Christians who had been forced to renounce their Faith during the Decian Persecution (250 CE).

In 251 CE, Novatian opposed the election of Cornelius as Pope, and was consecrated as Pope instead by three of the Bishops.
A Synod held in October excommunicated him and his followers and Novatian was branded as a Heretic by the Catholic Church.
However, the sect remained popular long after Novatian’s death, as they had their own Bishops who continued to elect their own Pope at Rome.
They never accepted the authority of the Pope of the Catholic Church.