There are indeed more Protestants than Catholics in the U.S. But, the Catholic Church is also the largest single church or "denomination" in the U.S., since Protestants are split between many different churches (e.g., Methodist, Baptist, Presbyterian, etc.).
Yeah, I pointed that out in my post. The original poster's point, however, was that if you picked a person a random, a catholic would be the most likely result. That is not accurate.
And for what it's worth, the religion component is completely unimportant to me. I just don't want someone that believes that "God's laws" trump the "laws of men" when it comes to making judicial decisions.