Banksy has waded into the child sex abuse scandal of the Catholic church with a sculpture of a priest with his face obscured called Cardinal Sin.

The graffiti artist's piece is a replica of an 18th-century stone bust, which has had its face sawn off and replaced with a mosaic of bathroom tiles to replicate the pixellation effect used on TV to prevent identification of victims of sex crimes.

Announcing his indefinite loan of the piece to the Walker Art Gallery in Liverpool, Banksy strongly implied that Cardinal Sin is a comment on the sexual abuse of children by Catholic priests.

Describing the statue as a Christmas present, the artist said in a statement: "At this time of year it's easy to forget the true meaning of Christianity – the lies, the corruption, the abuse."

The bust went on public display for the first time on Thursday in the Walker's 17th Century Old Masters gallery, alongside works by old masters including Van Dyck and Poussin.

Reyahn King, director of art galleries at National Museums Liverpool, said the Walker was "thrilled" to display the work of a "major contemporary artist".

"It's a huge coup and we are sure his work will spark a reaction with visitors.

"Banksy specified that it be shown alongside our period collection and we were very happy to oblige."