Because it’s “private,” obviously. It has nothing whatsoever to do with how she goes about her job. But, really, then: why bother? If what you believe and what you do have nothing to do with each other, one of them is a sham. At least since the first Roman Catholic was elected as president, this issue has been at the center of politics. If you look at how thoroughly what Washington and Lincoln, even Jefferson, believed suffused the way they governed, it is a serious deficit when people think that what they believe does not affect how they go about their vocations. This is not necessarily about Christianity. I expect atheists to govern as if there is no higher authority to which they owe obedience; therefore, the State or the good of the nation (however that might be defined by an atheist) will determine what he does. (However, the work of the atheist politician may still, by his recognizing of some order in nature, align with what the Christian thinks the government should do.) Likewise, if I serve in the government, and I believe human life is not mine to give, take, or manipulate–even for what I think are good ends–then I will work for laws that support that. If I believe that it is necessary to, first of all, protect all human life by virtue of its being human, then all other goods will be ordered by the standard of that good, whether that be foreign policy, health care, the economy, etc. What comes first in the order of goods determines how other goods will be ordered.
The fact is, Nancy Pelosi does govern by what she believes (it is literally impossible not to do so), but what she believes is not the same as what the Roman Catholic Church teaches. She is, in fact, not separating out her Sundays and the days when she is at the Capitol; she just hasn’t recognized the conflict between what she really believes and what her Church teaches. Actually, she probably does recognize the conflict, but she thinks her Church is wrong. That’s why she wouldn’t answer the question about the teaching of the RCC on contraception. She knows she’s on the wrong side of the Church on that question. Further, her highest good must be something other than a Creator of human life, if she can, in any way, support the intentional taking of that life. I don’t know what she would say is her highest good, but it’s clearly something different than the highest good of what she does on Sundays, in church. In other words, she is deceiving either herself or her constituents about what she really believes.
How much simpler it would be if politicians would simply state their highest Good, so we could evaluate how that Good might work itself out in their particular policy decisions. They all have one, and it unites their political positions into a whole (although, I admit, politicians may still hold contradictory positions because they haven’t thoroughly worked through what their primary goods mean for what they want to do). For those, like Pelosi, who support the unlimited abortion license, their highest Good clearly is not the same as those whose religion on Sunday proclaims a Redeemer who was conceived, born, lived, died, and resurrected for every member of the human race.