The Christmas shopping season officially kicked off with Black Friday and Cyber Monday, but this week, many nonprofit groups also urged Americans to make charitable contributions as part of Giving Tuesday. Meanwhile, a new study has found that almost three-quarters of American household giving is to organizations with religious ties. According to the report, by Jumpstart and the Indiana University Lilly Family School of Philanthropy, 41 percent of all household donations last year went to religious congregations. Thirty-two percent went to religiously affiliated nonprofits.