Victor, in all honesty, I think pah's list points out some of the ways you hold this privilege. I understand how it's easy to get defensive. I understand that there is a lot of Christian-bashing in this society. But try to set that asside for a moment and imagine what it would be like to live in this society as a Jew, for example. Imagine that you do not believe that Jesus Christ is your lord and savior. In fact, you think that idea goes directly against your view of God as transcendant and unknowable. (Just imagine that you believe this is true.)
Now imagine that come December, everyone wishes you a Merry Christmas and expects you to do the same, even tho the birthday of this man means nothing to you. The stores and tv shows are full of Christmas images. No one has to remind people that Christmas is coming up. You automatically get Christmas as a day off even tho you do not celebrate it. But right now in early October, at your holiest time of the year as a Jew, there's barely any mention of it. Your coworkers don't say anything to you. You have to remind them that it's your holiest day if you want them to know. If you want time off to observe Yom Kippur, you have to actually ask for it, making other people think that you're asking for additional time off.
As a Jew, your holy day is friday evening to Saturday evening. Following the commandments that Moses gave you, you do not do any work at that time. That includes not buying groceries, going to home deopt for fixit jobs, etc. Given that you work mon-fri, that leaves only Sunday for you to do these things. Yet a lot of stores close on Sundays, or they open later and close earlier. Not too long ago, there were even laws that prohibited stores from being open on Sundays. When a Jewish businessman sued on account that it unfairly penalized him to have to be closed on both Sat (for his religion) and Sun (for the law), the Supreme Court actually said, "too bad."
Those are just two examples. There are many more and similar considerations exist for members of other faiths.
Victor I hope you trust that I am not saying this out of anger or bitterness towards Christian dominance. As a UU, I am quite comfortable celebrating Christmas and Easter and attending church on Sundays. But since there are Jews and Hindus and Buddhists and atheists and pagans in my congregation, I know what they go thru, even in our congregation which makes a point to be open and welcoming of diverse faiths.
Again, no one is accusing you of any wrongdoing. I think pah's post was initially simply intended to raise awareness of these privileges. When you and Scott reacted defensively (and I totally understand why you did) pah reacted to your reaction and I probably did not help things here because my first reaction was "here we go again."
Thank you for asking sincerely.