In terms of attendance, Christmas is one of the biggest Mass days of the year. Invite any newcomers via a pulpit announcement to spend some time after mass with a member of the parish staff or other young adults who will welcome any questions on any subject with reference to the Catholic Church. Especially invite seekers and those who may have been away from the church for some time. Invite the parish staff or a group of young adults to directly welcome anyone who they can’t place by face to the event.