Complex sentence: Monsignor Guido Marini (born 31 January 1965) is a Roman Catholic priest, who has been the Master of Pontifical Liturgical Celebrations since 1 October 2007, when he replaced Piero Marini (no relation).
Split into simpler sentences: Monsignor Guido Marini (born 31 January 1965) is a Roman Catholic priest, currently serving as the Master of Pontifical Liturgical Celebrations. He was appointed to this post on 1 October 2007, replacing Piero Marini (no relation).