(Apparently an earlier writeup explaining what happened is now gone. This was a rally held in response to the We Still Pray rally, and I believe a previous writeup asked why this rally was necessary.)
If freedom of religion is in the First Amendment in the United States Constitution, why did this rally happen?
Legally, there is freedom of religion in the United States. But it is people that make up that government, and people that discriminate in their dealings.
Members of the government was perfectly willing to believe the pagans were behind Ritual Satanic Abuse. More specifically to things like Wicca, read up on the West Memphis Three. School districts that allow students to wear cross pendants ban pentacles and even occasionally the Star of David as "gang symbols." Representative Bob Barr wanted Wiccan practices stopped at Fort Drum, and Wiccans even banned from the military. The "witchcraft" card, sometimes true in reference to Wiccan practices, has been played effectively in determining custody after a divorce.
Religous freedom is not necessarily still around. Heck, if there are still cases of gross anti-Semitism in a few isolated towns, such as at Big Bear High School.
These things are why pagans tend to be so paranoid about their religious freedom. Want to see more examples of these events? Check out Wren's Nest, a service of The Witches' Voice. It's not completely "bad things happening", but you can expect a few per week.
For more reading:
Wren's Nest News, http://www.witchvox.net/xwrensnest.html
The West Memphis Three, http://www.wm3.org/