On the topic of gay marriage Bill O'Reilly seems to be taking great umbrage at conservatives who seek to uphold marriage AND to respect those who recognize the Bible as God's Word. Go to this Business Insider article. Embedded therein is a clip of him literally having a temper-snit at Laura Ingraham. I can only conclude that he knows he is incorrect and is lashing out over a stung conscience. In this BI clip, you'll see the video of Rush Limbaugh to which O'Reilly and Ingraham allude in the first clip.
In CNS News, Father Marcel Guarnizo has published his own rebuttal of O'Reilly. He focuses not so much on the "Bible-thump" quip as much as he dwells on more fundamental issues. Father examines what seems to be libertarian underpinnings of O'Reilly's erroneous attitudes towards "gay marriage" and the inevitable harm that will be wrecked on all concerned: including gay people themselves. It will not be a "quick read" but one well worth your time.
While I'm sure this hasn't occurred to Father, he makes a cogent (if unconscious) argument why the libertarian philosophy cannot be considered true conservatism. It cannot even be considered moral.