MADISON, Wis. -- The bishop of the Roman Catholic Diocese of Madison is making national news for blasting two Democratic leaders.

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But Bishop Robert Morlino said it's not about bringing politics to the pulpit -- it's about being a good Catholic.

Specifically, Morlino said it's about making sure Catholics aren't confused about why the church is opposed to abortion, so Sunday he blasted two Catholic political leaders for being "confused" about church doctrine.

Morlino on Sunday told parishioners: "I am obligated to teach... They are stepping on the Pope's turf and mine... they are violation the separation of church and state... and confusing God's good people."

Morlino is being cited by a national newspaper for an impromptu homily that he delivered about Catholic politicians and abortion at St. Patrick's Catholic Church in Madison.

He threw out his original text and delivered the sudden sermon, he said, after watching first Democratic House Speaker Nancy Pelosi and then Democratic vice presidential candidate Sen. Joe Biden -- both Catholics -- speak about their basis for being in favor of abortion rights on NBC's "Meet The Press."

Joe Biden told host Tom Brokaw that he believes life begins at conception because of his faith, but that he can't impose that religiously based belief on everyone.

"I feel that is inappropriate in a pluralistic society," he told Brokaw.

Earlier, Pelosi had said she was pro-choice but that she had struggled with it, just as the church has had struggles with it in the past.

Morlino said Thursday, "I'm not singling them out because they are Democrats. I'm signaling them out because their confusing the teachings of the Catholic Church on a wide-ranging national basis."

"Sen. Biden, in particular, didn't seem to understand that our stance on abortion is based on reason and science not on faith," said Morlino.

The bishop insists science, not religion, is the basis for knowing conception is the start of a unique human individual, and that scripture dovetails with that.

Morlino has been criticized in the past for getting too political on key issues, WISC-TV reported.

In the 2006 election, he was criticized for requiring every parish play his message on controversial issues, including traditional marriage and embryonic stem cell research.