I can verify that is the correct Pledge to the Christian Flag and that the flag is about 100 years old.
The pledge is an affirmation of faith. Why would you consider it disturbing? It is used by homeschoolers and by churches in various settings, but I'm not aware of any efforts to incorporate the use similiar to the Pledge to the Flag.
Under the terms of the 1st Amendment, why would you find an affirmation of faith disturbing? Seriously.
As a Catholic, I can see how some protestants might see the whole pledging (swearing) allegience to a religious flag thing might conflict with the First Commandment and the whole graven images taboo. I know it's not meant that way, but the concept gives even me the creeps with it's connotations of religious nationalism.
"...with life and liberty for all who believe."
I would find it disturbing not because it isn't free speech which it is (and more power to one for saying it) but because of the allusions it makes to our Pledge Of Allegiance which is not religion specific. To an outsider not familiar with the ways of your faith it certainly could appear as though it is a replacement for the United States Pledge Of Allegiance.
Put it in these terms: Take an American Flag with the stars and stripes, keep the stripes but replace the Stars with holy crosses. I am a Christian but I could never support nor worship such a flag as I would consider it a mockery of the U.S. flag, no matter how noble or worthy the intentions of said flag's creator. Similarly, a pledge of faith that uses the same structure (and in some areas the same verbage) as the United States Pledge of Allegiance, in my view makes a mockery of our official pledge of allegiance.
This is like the "One Nation...Indivisble" bru-ha-ha that erupted a few weeks ago, only in reverse. Many compained that it made a mockery of our Pledge by taking God out of it. Well in the opinion of some, which I would be one, this pledge makes a mockery of our pledge by injecting Christianity into it and taking our government out of it.
Under the 1st Ammendment of our great nation, you are entitled to your pledge and I find nothing personally wrong with advocating your faith and celebrating Christianity. I just wish the verbage was more original, tactful, and didn't blur the lines between an official government pledge and a celebration of one specific kind of faith.