The Prophets of G are Quarrens who are spreading the word of G. Prophets of G are spread throughout the outer rim ranging from planets such as:

Mon Calamari
Umbara
Ryloth
Ord Mantel
Mandalore
Dathomir
Coruscant
Pantora
And throughout the outer and mid rim

There are 2 Types of G's;
The Prophets:
Prophets are peaceful and merely talk, preach, and converse with others about G.
The  Raiders:
Raiders are  Prophets of G who conduct violence on those who oppose  G.

Prophets of G believe in someone or something called the G in which "G" will bring salvation and end all suffering throughout the galaxy. People have mixed feelings in G'ism for Raiders claim that G will end bring salvation and end suffering throughout the Galaxy through Death (You cant suffer when you are dead.) Prophets of G Claim that suffering will end throughout the galaxy by salvation, G will end all conflicts liberating the Galaxy of Corruption.
Prophets of G use Formal clothing in all planets they are present on, with Raiders being known to use Formal Clothing, and sometimes Red Bushes.

There are rumors that Prophets of G are force sensitive but this claim has not been proven...