Five years after Pope Benedict lifted most restrictions on celebration of the Tridentine Mass, a senior Vatican official says much work remains to make the traditional liturgy fully accessible to the faithful, and to bring its influence to bear on the form of the Mass most Catholics attend.

"There's no question that there remains in certain places a resistance to what the Holy Father has asked, and that's sad," says Cardinal Raymond Burke, prefect of the Supreme Court of the Apostolic Signature.

"It's sometimes even an expression of disagreement with the Holy Father's discipline and even an expression that this is harmful for the Church."

With his apostolic letter Summorum Pontificum, issued July 7, 2007, Pope Benedict allowed priests to offer the Tridentine Mass without special permission from their bishops.

The decree also provided for the establishment of "personal parishes" dedicated to the traditional liturgy.

"What earlier generations held as sacred, remains sacred and great for us too, and it cannot be all of a sudden entirely forbidden or even considered harmful," the pope wrote at the time.