What does this mean?

Question

Speak of the devil, and the devil is there.

Answer 1

It refers to a Christian-based belief that just talking about the devil and his works invites his presence and his power. So people would say don't even talk about the devil or mention his name.

Nowadays people use part of the expression when someone shows up just as they were talking about him/her. "Well, speak of the devil, look who is here!"

god bless