While I have indeed seen such signs in religious catalogues and imagine that it would be cheaper to make your own from materials around your house, I cannot recommend hanging signs on one’s home that contain wording that gives the unfortunate impression that the homeowner is hostile to people of other faiths. This does not mean that you cannot protect your free time from doorbell ringers. Why not simply purchase the much more common and readily available sign that says “No solicitors”? If you open your door and find a religious proselytizer on your porch you can then point out the sign, smile regretfully, say “Sorry, I’m not interested,” and shut the door.