And here is a sample letter:
To whom it may concern:
I strongly oppose plans to rescind conscience-protection regulations.
The proposed rescission of conscience-protection regulations is inconsistent with the status quo, where conscientious objectors are not discriminated against for refusing to engage in combat or administer lethal injections.
Health care professionals should not be forced to participate in acts that violate their consciences, and their right to follow their consciences should be protected by law. Additionally, patients should have the freedom to choose doctors and health care providers who share their values.
Please retain the conscience regulation, and enforce current laws protecting the right of health care providers to serve patients without violating their moral and religious convictions.
Or, if you prefer, here is a site that will put together your message for you, leaving room for your own comments.