The main theme they will hit on is that they claim ENDA will force religious employers to hire people they don't want (despite ENDA's religious exemptions), and that religious co-workers may be "persecuted" for speaking their beliefs.
But what constitutes "speaking your beliefs"? Does that include telling your coworker they're a sinner? Blogger BlackTsunami discusses this.
Disclaimer: While I used the phrase "telling your co-worker they're a sinner", there doesn't seem to be evidence in the post that the guy in question said that to her. Though it does seem he used the term "deviant" in his letter describing the incident to his superiors at work.
Update (Nov 7, 2:40P): section of ENDA dealing with religious exemptions, section 6:
"This Act shall not apply to a corporation, association, educational institution or institution of learning, or society that is exempt from the religious discrimination provisions of title VII of the Civil Rights Act of 1964 pursuant (42 U.S.C. 2000e et seq.) to section 702(a) or 703(e)(2) of such Act (42 U.S.C. 2000e-1(a), 2000e-2(e)(2))."
Also the Senate had a hearing on ENDA on Nov 5, and Al Franken is on the committee! Third Senator to speak. Enjoy.