What are everyone's alignments? If everyone is Chaotic, I might pitch that Brother Tim's healing doesn't constitute a sin as long as it's related to combating the evil creatures in this dungeon or preventing a certain rival cleric from converting members. Without healing, he doesn't actually provide much value to the group.
Quote:
Such a healing action may constitute sin if not done in service of the faith. If cleric and subject are of opposed alignment (e.g., one is lawful and one is chaotic), or have rival gods, they count as "opposed" on the table. Such a healing almost always counts as a sin unless it is an extraordinary event in the service of the deity.