A bare foot squishing the blasphemer ala monty python.
How are lice at all threatening, besides causing itchyness?
How about the black plague and rat swarms? That's an obvious one.
How about forcing them to grow very long beards (even if they're female) and recite religious mantra completely opposite in belief to those currently main stream in the universe, thus earning the victim persecution by the populace? It's funny and it sorta makes sense.
Intense beams of light that blind and cause severe sunburn. Like skin cancer serious.
Very heavy hail.
Leprosy.
Victim becomes a blind and unwilling prophet that can communicate with angels (or whatever divine creature fits the deity) and must carry out menial divine duties on the material plane (like an unwilling messiah that's a sort of cleric). They are likely also given extreme attention by the populace, which is unnerving on their part.
----------
Read the old testament for some of the evil crap that god did, since I can't remember any of it (and haven't really read it).