This achievement is story related and unlocks at the conclusion of the
Kill Remy Duvall mission. After Lincoln burns Remi Duvall on a cross, there is a cut scene describing the event. Following the cut scene, a banner appears stating that the mission is complete. The achievement is then unlocked.
There are prerequisites for the
Kill Remy Duvall mission, Lincoln must secure both Frisco Fields Rackets--Southern Union and PCP. To complete the
Kill Remy Duvall mission, Lincoln must then find and interrogate a Southern Union Deacon. He learns that Remy Duvall is at a Southern Union Rally. He goes there, incapacitates Duvall, and takes out enemy forces. Finally, Lincoln confronts Duvall and makes his statement. After the ensuing cut scene, we are informed that the mission is complete and the achievement unlocks as shown in the following video: