An arsonist tried to burn a sacred icon taken from a Catholic church's holy altar and left a picture of the devil in its place, the diocese said.
It is the second time that St Mary's church in Great Yarmouth, Norfolk, says it has been targeted in a similar way.
The Diocese of East Anglia said that a man walked into the open church on Tuesday, lit two small fires and tried to burn an icon before leaving the satanic image.
Norfolk Police is investigating the incident as a hate crime.
Parish priest Friar Anthony Nwankwo said: "I was shocked and saddened when I discovered what had happened.
"When I looked at the altar I saw this picture of something satanic.
"My immediate thought was to get some holy water and use it with prayer to nullify what the person had done.
"It is a clear attack on the church and our religion which is not acceptable."
He said he felt the church had been "desecrated", and that something similar happened four months ago when someone left a satanic picture at the foot of a cross at the back of the church.
The Bishop of East Anglia, Right Reverend Alan Hopes, said the church would remain open.
He added: "I am hoping it is not a hate crime, but whoever did it needs to know that he is already forgiven because that is part of who we are as Christians".
Brian Lafferty, who has been a parishioner for 33 years, said he was appalled.
"I have never seen anything like it before and it is quite disturbing really, especially in this day and age," he said. "I was totally shocked and disgusted when I saw it and there is no room for it in today's society.
"If you want to celebrate like that and worship other gods there are other places you can go.
"Here, we worship the one God."
He said the church had CCTV pictures of the man they believe to be responsible, and have passed these to police.