Just want to draw your attention to an excellent recent speech given by Catholic Voice Melissa Moschella on religious liberty in the U.S. today.  It's a comprehensive treatment of religious liberty issues ranging from the HHS mandate to immigration. Melissa discusses why conscience rights are so important:

Conscience rights go to the core of what is to be a human person: the capacity to act based not only on desires or instincts, but on judgments about what is good and bad, right and wrong — and the moral responsibility that is inseparable from that capacity. To force a person to act contrary to conscience is to force him to violate his moral integrity. It is an assault on the person at his core, which is more devastating than physical harm...That’s why America’s founders were so adamant about the protection of religious liberty and conscience rights as fundamental to a free and just society.

It's a great resource, and worth reading in full.