How scary can you be?

One bright, beautiful Sunday morning, everyone in tiny Smithville
wakes up early and goes to their local church. Before the service
starts, the townspeople sit in their pews and talk about their 
lives, their families, etc.
 
Suddenly, at the altar, amidst an explosion of fire, Satan appears!
Everyone starts screaming and running for the front entrance, 
trampling each other in their determined efforts to get away 
from Evil Incarnate.
 
Soon, everyone is evacuated from the church except for one man, who
sits calmly in his pew, seemingly oblivious to the fact that God's
ultimate enemy is in his presence. This confuses Satan a bit.
 
Satan walks up to the man and says, "Hey, don't you know who I am?"
 
The man says, "Yep, sure do."
 
Satan says, "Well, aren't you afraid of me?"
 
The man says, "Nope, sure ain't."

Satan, perturbed, says, "And why aren't you afraid of me?"
 
"Well, I've been married to your sister for 25 years, how bad 
could you be?"