NEW YORK -- More than 64 million American Catholics share one faith but they hold many different opinions when it comes to their church’s core teachings.

When a top Vatican official recently characterized causing poverty, the pursuit of obscene wealth and pollution as sins, it produced a worldwide reaction.

Despite the largely satirical reaction, it is a good example of the challenges of interpreting the Catholic Church’s doctrine, its essential teaching, some of which are 2,000 years old.

For many people, the Catholic Church is defined by what it is against, such as abortion, many forms of birth control and the ordination of women as priests. Some Catholics argue it has created a misconception of what the Church is really about.

“I always say we have been very clear about what we are against, and we haven’t been as clear as a church in saying what we are for,” Julia Upton of St. John’s University said.

Sacredness and the dignity of human life is perhaps the most central tenet of Catholic doctrine. It’s why the Church opposes capital punishment, why it urges those who are successful to take care of the poor and for business owners to consider the welfare of their employees and not just their profits.

Yet many Catholics are at odds with the Church on key issues.

A recent WNBC/Marist Poll found that among Catholics in the New York City area, three quarters disagree with the church’s position opposing non-natural forms of birth control.

Nearly half disagree with its stand against abortion rights and capital punishment.

Sixty-seven percent disagree with the Church’s position against female priests and 57 percent support gay marriage, which the Church also opposes.

One Catholic scholar said it is important that Catholics examine the reasons why they may vary from the Church’s official doctrine.

“It’s not enough to say, ‘This is my preference,’ but to think about things, to inform one’s self and then to make a decision,” Sr. Celia Deutsch of Barnard College said. “That’s another kind of move and that simply says to me that being a Catholic is a real complicated thing.”

But bringing the world’s billion Catholics more into line doctrinally is a priority for Pope Benedict XVI, who previously headed the Congregation for the Doctrine of the Faith, the Vatican office in charge of safeguarding the church’s teachings.

But insisting on stricter adherence to church doctrine might drive some Catholics away.

The new sins outlined by the Vatican do show a willingness to adapt to a new age, but it comes at a time when the Vatican is also recommitting itself to the rules that have governed the Church since its beginning.