Rewards:
This becomes available after completing “Grace Under Fire” in the Lamb of God church. Find the NPC with the mission marker beside the church and talk to her to get this mission started. From her position, follow the dirt trail (eliminate any cultist patrol you encounter) until you reach the rock outcrop overlooking the Lamb of God Sacristy. This is a good spot to use your binocular and spot all the hostiles and hostages below.
Use the zipline while the cultists are not looking then carefully pick off the lone patrolling cultists. The last targets should be the cultist VIP and his bodyguard. You can go loud at this point, just make sure to quickly kill the bodyguard with a headshot then shower the VIP’s body with hot lead.
Liberate all hostages next. The weapons cache that they need to go to is located on the mountainside across the river. There’s a nearby dock nearby where you can spawn any boat you own or simply attack a cultist river patrolboat and repair it for your own use.
Follow the mission marker then stop by a dirt road. There’s a bear ahead so prepare to kill it or scare it away. Continue up to finally reach the weapons cache. Mission complete.