. But there is no direct connection between the promise related to the free gift; and a voluntary donation which is not mentioned anywhere in the ad.
The purpose of the ad is to appeal to an audience that is ripe for his letter scam, which is where the real money comes from. In his letters, he clearly makes a connection between the amount of the donation and the "greatness" of the blessing. It isn't that he refrains from making promises, it isn't that the promises are not connected to the money, it's just that his promises are so undefined that they are meaningless. The law can't make binding that which does not make sense.
There is no law against me writing as many people as I want and requesting money, as long as I don't harass, I personalize the letters, and report what is necessary on my taxes. As far as the law is concerned, that is exactly what Peter does, and he keeps up with his taxes. It really isn't much different than what Silvia Brown or John Edwards does. He is committing no direct legal fraud, people are freely donating, and in this case the US has decided that people are free to make bad choices if they want to. (too bad the law doesn't take that approach with drug policy)
The real culprit here is ignorance. The general population is not well equipped to think about situations critically. The average person is not aware of the logical pitfalls, the perceptional mistakes, and the instinctive biases they are subject to every day, while con artists like Peter are well aware of these flaws and how they can be exploited. What I would like, instead of laws against religion, is for people to be capable of seeing through bullshit intuitively.