MILWAUKEE -

New York Cardinal Timothy Dolan says the biggest pastoral problem facing the Roman Catholic Church is the growing number of people who identify as former Catholics.

Dolan says those who identify as ex-Catholics would amount to the second-largest  denomination in the U.S.

But Dolan says Roman Catholicism holds that Christ and the Church are one and can't be separated. He says Catholics can no more leave the Church than they can leave their family.

Dolan says, "Catholicism is in our DNA. It is in our bones."

Dolan was speaking to a crowd of about 4,000 people in Milwaukee, where he's giving the archdiocese's annual Pallium Lecture. It is a lecture series on spirituality that he started while serving as archbishop of Milwaukee from 2002 to 2009.