The Gallup Poll, as Bill Cork pointed out, has revealed that Church-going Catholics are far more likely that Church-going non-Catholics (almost all Protestant) to accept immoral behavior.
I do not find this surprising. Other polls I have seen over the years reveal similar patterns.
This data helps explain Notre Dame’s invitation to Obama. Many Catholics accept Obama’s positions.
The failure of catechesis over the past two generations is one of the principal reasons. Making felt banners does not help produce a reverence for God and the moral law. Catechesis may have improved in the schools, but fewer Catholic children are going to Catholics schools or to religious education classes. Instead they are picking up their attitudes from their poorly-catechized parents, among whom are prominent politicians.
But this still does not fully explain the difference. Why are Church-going Protestants better able to resist accepting prevalent secular attitudes to morality? Catholics once submitted to the teaching authority of the Church; many Catholics, even those who regularly attend church, have clearly rejected that, and have nothing to replace it except the standards of American society. Perhaps Protestantism, built upon a veneration of the Bible, has been better able to resist the moral acids of secularism. Catholics claim that the living authority of the magisterium is better able to meet moral challenges, but this does not in fact seem to be the case. Roma locuta est, but very few Catholics are listening. When the Bible speaks, (and it does speak clearly on many issues) many Protestants listen.