Here is the full list of all 21 Substitute Priest achievements.
Leave your place
You freed him
Leave with the journalist
Leave with the car
Dying in an ADVENTURE!?
Pour Gasoline over the wool
Talk to the construction worker every day
You found the missing piano key
You got rid of the poor lady
You had help with the frat-guy
You defended yourself
You prayed together
Interact with the cigarette a little too much
Find something the priest is not able to see
You opened the drawer
You left the old priest lying
You took him with you
Have a small philosophical conversation
Try to close the door from the outside
Before going to sleep, brush those pearly whites
Regain Control