Christians Only At TX Prayer Rally

And here's why, according to an event organizer:

This is an explicitly Christian event because we are going to be praying to the one true God through His son, Jesus Christ. It would be idolatry of the worst sort for Christians to gather and invite false gods like Allah and Buddha and their false prophets to be with us at that time. Because we have religious liberty in this country, they are free to have events and pray to Buddha and Allah on their own. But this is time of prayer to the One True God through His son, Jesus Christ, who is The Way, The Truth, and The Life.

I'm still trying to figure out how a state-sanctioned, explicitly exclusive religious event is being allowed to take place. Where are the lawsuits?

EDIT: It was pointed out to me that the above-quoted person is one of the prayer rally's organizers and that he was not speaking as Texas Gov. Rick Perry's spokesman, even though Perry is the event's headliner. Therefore I've changed the opening line of this post.