No name. Most times they are termed lost souls. But even then there is hope for every lost soul.
They are called "Satanists".
The God.
The followers of Hinduism are called Hindus
Satan-Sataniel
Followers of god Shiva are called Shaivites.
Mussolini's fascist followers were called "Blackshirts."
The followers of John Calvin were actually called Puritans.
Hazrat Isa AS is called Jesus Christ. His followers are called the Christians.
Rasmus sings Lucifer's Angel
John Calvin's followers were called Huguenots in France.
They are called "Satanist" If they are followers of Satan, then they are generally called Satan or devil worshipers. If they are followers of satanism which is different then they are refered to as a satanist.
If you are referring to Francis of Assisi, his followers are called Franciscan. If you refer to St. Francis Xavier, his followers are called Jesuits.
Followers of the Buddha are called Buddhists.