Murder mystery in a church. Eucharist is poisoned, most church attendees die.

[Renee]

Hi there, I have a friend who is looking for a book they read a while ago (not specific about whether it was three years ago or 10) They couldn't remember the title, and tried Google with no luck.
here is the plot:
A Jewish man goes to church with his Catholic girlfriend. Only two people didn't take Communion (the man and a stranger). the Eucharist is poisoned. Everyone in the church is killed. Someone comes to the church to finish off the survivors. the main character pretends to be dead.
Any help would be great.

[Kris]

Renee, is your friend still looking for this book?