The Gallup poll I cited below is puzzling. Why should Church regularly-Church-going Catholics be laxer in their attitudes to morality than regularly-Church-going Protestants?
The Church regards Tradition as the source of revelation. Tradition is That Which is Handed Over, tradere, and includes Scripture. Scripture is part of the life of the Church, and is to be understood as the Church understands it. I think even Protestants would see the logic of this view of Tradition, although they would place greater emphasis than Catholics do on Scripture as the norm of faith.
When moral questions arise, a Catholic should consult revelation, as interpreted by the magisterium. But what is the magisterium? Some regard it as the pope and the bishops who are in union with him. Others would include theologians. Before Vatican II, there were few disagreements about moral question in the Church, usually on rare cases.
In practice Catholics did not consult Pope, bishops, or theologians, but the prelist in their parish or what they read in Catholic publications. Again, before Vatican II there were few disagreements about morality. Anyone in the clergy would give basically the same answer to a question about morality. There were minor differences, and Catholics were taught you could follow any reputable opinion if there were differences. These usually concerned disciplinary questions, such as the requirements of fasting.
But after Vatican II total chaos ensued. The Catholic Theologian Society issued a book that could not bring itself to condemn any sexual practice including adultery and swinging. André Guindon, who taught in a seminary and wrote a book extensively used in catholic seminaries, claimed that the main problem with pedophilia was the fuss the parents made (all discussed at length in my book).
Especially in the area of sexuality, a Catholic during the past 40 years could find a priest who would countenance or even advocate any imaginable (and many unimaginable) sexual practice. With this multitude of voices, Catholic, being human beings who are therefore adverse to curbs on appetite, chose to follow the voices promoting laxity, with the results that the poll shows.
Protestants, more accustomed to consulting Scripture directly, did not undergo this revolution. Although liberal Protestant theologians attempted to undermine the moral teachings of Scripture, they had to deal with the unchanging words on the page, which still carry divine authority for many Protestants.
