The canonisation was considered a life-time event for Catholics. "Here we've got the canonisation of two popes being witnessed by two living popes. It's very significant," Fr Carmine said.
The canonisation was carried out by the current pontiff, Pope Francis, and witnessed by the retired Pope Benedict XVI.
Pope John Paul II and Pope John XXIII were "inspirational leaders" for the Catholic Church, Fr Carmine said. "In their own different ways, they were very influential."
Pope John XXIII was pope from 1958 to 1963. He was known for his intervention to save persecuted Jews during World War II and for beginning the Second Vatican Council, which started the liberalisation of the church. The more conservative Pope John Paul II was pope from 1978 until 2005.