The "people's pope"? Not among some conservative Catholics

As Pope Francis says farewell to Cuba, he kicks off his historic visit to the United States.

Ahead of the Pope's arrival in Washington Tuesday afternoon, a CBS News-New York Times poll has found that 79 percent of Catholic Americans approve of the direction that Pope Francis is leading the church. More than half of them strongly approve.

But some Catholics also worry the church is changing too much, reports CBS News correspondent Jan Crawford.

Since being sworn in,the pope has shown that he is not just an average pontiff. He has signaled a new tone in the Vatican, urging the church to show more mercy and forgiveness towards people who fall short, especially in light of issues that have traditionally been frowned upon by the church.

On abortion,the pope said priests could forgive "the sin" for women who say they are sorry.

On divorce, he has suggested priests could allow remarried couples to receive communion.

And on homosexuality, he famously told reporters in Italian, "If a person is gay and seeks God and has good will, who am I to judge him?"

While his message has attracted a massive fan base, earning him the nickname, "The People's Pope," it is causing real push-back from some religious conservatives who worry he is watering down Catholic doctrine.

"All day long we make judgments with regard to certain acts. This is what the natural law is to choose God and avoid evil," Cardinal Raymond Burke, a conservative Catholic, said during a 2014 interview with Eternal Word Television Network.

This fall, more than a dozen cardinals and bishops from around the world will publish books defending church doctrine, and nearly 500 priests in Britain are urging church leaders to issue a "clear and firm proclamation" against communion for divorced couples.

But the pope has yet to change church policy. He has called abortions "abominable crimes" and emphasizes marriage is a "bond between man and woman."

Still, some conservative believers say the pope's message of mercy and forgiveness is sowing seeds of confusion, especially on moral issues.

"They worry that perhaps he is devaluing marriage, perhaps he doesn't recognize that homosexuality is a sin," said Candida Moss, a theology professor at Notre Dame University. "Francis hasn't changed anything doctrinally, but just the shift in tone has given conservatives cause for alarm."

Francis Rooney, a former U.S. ambassador to the Vatican, disagrees, and said the pope is merely calling for a less judgmental attitude.

"I think the pope is looking at the realities of life and saying, 'Whoa, you can't ban these people to the basement. You've got to embrace the differences without changing your theology,'" Rooney said.

The pope may cross paths with conservative Catholics on two other issues: income inequality and climate change. Rooney says the pope's focus on the disadvantaged and vulnerable explain why he is sounding the alarm on such issues.