Just Cause 3

To unlock a priest, complete random Encounters like hostage or prisoner rescues. Once a priest is unlocked, use a tank or jet to quickly build up heat, then talk to the priest.

I just got it without too much efforts with these parameters:

Region : Insula Striate (big island)
Province : Maestrale

- First, make sure you do the random encounter which gives you a priest in the North West area of Maestrale.

- Then, liberate Porto Tridente (N 40 49.446 E 5 32.185) if you want.

- This will unlock the Volo Martino air race (N 40 48.721 E 5 33.240) which is South East of Porte Tridente. The reason why I mentioned to liberate Porte Tridente, is to have the air race icon available on the map in case you might need it to fast travel.

- There you will find a nice jet being the U-7 Dravec which has some nice quick missiles.

- From there, head North East to Platteforma Maestrale I (N 40 50.789 E 5 35.638) which is at 5,35km/3mi

- As you approach this platform, start sending missiles (the more the merrier). You should instantly get Heat Level 5 as you hit the base.

- Once the heat is on, immediately start heading for the priest whom you will find at Sancte Martino (N 40 49.313 E 5 34.852) and which is only 3km/1mi away from the platform making sure the heat won't drop.

My 5 stars of heat were grey, not red and it still did unlock the achievement.

Any suggestions to improve this guide are welcome.

Thanks for voting thumbs up if this guide was helpful.

Good luck!!

I really struggled with the above guides as the priest was too far away and I lost my five stars. However I found a much easier place to get it. On Insula Fonte there's a town called Rondella, it has a church right next to it. I had a hijack mission appear in the town and once I completed it I unlock a priest. Also happens to be the first priest I unlocked. Cause havoc in the town while slowing making your way to the church, when the tanks start to appear you should be on four star. Keep killing them until you get five stars, I used the Eden Spark for maximum chaos. By the time you have five stars you should be right outside the church. Very easy way!

I found this a little annoying to do, it was one of the last achievements I unlocked because I just couldn't reach a priest without losing my heat already. A few guides suggested attacking bases near monasteries, but entering the base just triggered a combat zone, not heat, so I must have been misinterpreting :P

Anyway, I found the best location was in Capite West on Insula Dracon. There is a small guard post called Guardia Capite II just north of Arco Sperantia, and just next to the guard post is Sancte Antonio (sorry I didn't take a screenshot of the location here). Here I triggered heat 1 by shooting some of the guards near the tower where the road splits towards the monastery, making sure to not kill guards who are calling for reinforcements. Then I killed soldiers, and hijacked tanks and helicopters as they arrived, making sure to kill and blow up enough guards to raise heat without getting rid of them all, to keep the heat going.

It can be a little annoying and tricky to stay alive when the big guns start arriving, so by heat 4 it might be wise to stay in a helicopter and be evasive. As soon as the heat meter hit 5 I jumped out and grappled to the priest, who is on the right hand side of the monastery as you approach it... and voila, achievement unlocked