
Quoting
Taxing Matters
There are two problems with this. First and foremost, you are making the illogical assumption that all religious canvassers are gathering detailed data to enter into some database. There is nothing about canvassing to spread your religious beliefs that automatically compels the conclusion that information gathering is being conducted. Could some group be doing that? Sure. Do most such groups do it? No, they don’t.
Second, like many Americans, you seem to believe that your rights to privacy are much greater than they really are. The law actually only protects your privacy in certain specified instances. For example, there are rules that specify privacy for certain information that the government, financial institutions, health care providers, and schools have concerning you. But much information about you is not protect by any law. For example, most information your employer has about you is not protected by any law. Your name, address, phone number, etc., are not protected from disclosure by most persons who have that information (aside from those institutions I've already mentioned). No law prohibits an organization from gathering such information, either.
It is up to you what information to give out when answering your door or even whether to open your door at all. The person at your door cannot record information you refuse to give, after all. You are the best protector of your own information.
You won’t get reglious canvassers barred on a theory that they are gathering information to be recorded somewhere because of those two flaws. Most groups aren’t canvassing to gather up information to put into some database and even if they were, that’s not illegal or a violation of any of your rights.