Responding to a message about "Afrikan spirituality", Matthews, posted under the name of Noctis Matthews, said that he could not "bear all these Baptists here, a gang of brainwashed people trying to finding happiness in a religion imposed on their ancestors was on mine. "
Matthews said he hoped that "more blacks [sic] people would look at the old beliefs of pre-Christian Africa
An acquaintance, Nygyl Bryyn, has confirmed the profile to CNN and the pseudonym is Holden Matthews. He says his friend is not racist and thinks the churches have been "victims of the circumstances".
The three churches said the authorities said Matthews had been burned. These are black Baptist churches located in the heart of the Cajun and Creole country of south-central Louisiana.
The suspect is the 21-year-old son of a deputy sheriff of the parish of St. Landry and may have been influenced by music "black metal" and his "history associated with church fires", said the office of the state's fire marshal.
CNN has contacted Matthews' lawyer and the prosecutor's office, but has not yet received a response. When CNN asked the authorities if they were aware of the posting, they replied that the ongoing investigation forbade them to detail the leads that they were following.
While the motive is still under investigation, the authorities have stated that Matthews' interest in black metal music may have influenced his behavior.
Black metal is a sub-genre of heavy metal music that typically addresses anti-Christian, satanic and pagan themes.
Black metal songs usually have a fast tempo and include loud voices, highly distorted guitars and unconventional song structures.
A song from the suspect's group, Pagan Carnage, refers to church fires.
The day after the police announced that Matthews had burned the St. Mary Baptist Church in Port Barre, a video had been posted on his group's YouTube page titled "Diabolical Soul Feast."
"The holy church is now destroyed," cries Matthews in the last words of the song. "Burn in the name of Odin."
Bryyn says Matthews writes and plays the song.
The reason for these fires is still under investigation and federal officials are questioning whether a hate crime has been committed. Matthews is charged with three counts of arson alone on a religious building.
Greater Union was one of three historically black churches in the rural parish of St. Landry, west of Baton Rouge, which police say was intentionally burned for 10 days.
St. Mary Baptist Church in Port Barre, about six miles southeast of Greater Union, was burned down on March 26. The Baptist Union of the Great Union was burned on April 2nd. Mount Pleasant Baptist Church was burned on April 4th.