Cardinal Timothy Dolan (America's highest ranking Catholic) warned of the possibility of the US Supreme Court recognizing marriage equality in a bulletin that he sent out to parishioners around the nation.
U.S. Conference of Catholic Bishops warned:
“A broad negative ruling could redefine marriage in the law throughout the entire country, becoming the ‘Roe v. Wade’ of marriage. The United States Conference of Catholic Bishops has joined with many other organizations in urging the Supreme Court to uphold both DOMA and Proposition 8 and thereby to recognize the essential, irreplaceable contribution that husbands and wives, mothers and fathers, make to society, and especially to children.”
The bulletin then goes on to order American Catholics to actively try to coerce others to support the church's policy of discrimination:
“Be a witness for the truth of marriage in word and action. Take advantage of opportunities to speak about marriage’s unique meaning in conversation with friends, family, neighbors or co-workers. Share the truth in love.”
The bulletin also points out that supporting Marriage Equality also means you are not a true Catholic:
"It’s Catholic social teaching 101: pro-woman, pro-man, pro-child. Redefining marriage in the law says many false things: women - mothers - are dispensable; men - fathers - are dispensable; what adults want trumps what a child deserves and has a basic right to."