In the 10 years since his election, Francis has been criticized by conservative sectors of the US Church who are opposed to the pope's reforms.
The art teacher was engaged at the time her pregnancy was announced, leading to the school firing her.
Christians in Jerusalem are reporting more acts of vandalism and spitting. What are Israeli officials doing about it?
The billboard was put up on the Almirante Reis avenue - one of Lisbon's longest and busiest streets - and reads: "4,800+ children abused by the Catholic Church in Portugal."
The Vatican said about 330,000 young people have registered for an event in Portugal dubbed "the Catholic Woodstock."
A group of over 20 Christian and Jewish clergy and scholars from around the world came together to delve into the treasures of the Vatican's Hebrew manuscript collection.
The overall dispute is symbolic of larger power struggles.