I'd put some variation of the following:
If they stop at your door, ask them why they actively expose pedophilia problems in other religions but have paid eleven million dollars to victims in their own organization. Ask them why their leaders required the vicitms to sign waivers forbidding them from talking about the abuse they encountered. Ask them whether they are allowed to read literature that is critical of their organization. Ask them what happens to a person that DOES read such literature and is discovered to be reading such by the elders.
Ask them what their viewpoint is on sending their kids to college. Ask them whether they are at your door to try and convert you. When they tell you no, ask them if it is OK for them to lie about wanting to convert you or not. As one who was a part of the organization for many, many years, I can assure you that that is why they are there. They want to offer you a bible study so they can teach you about their cruel, vicious God, get you frightened about Armageddon, and convince you that your only hope is to join with them to avoid being destroyed by God and his chief angel, Jesus Christ. Yes, that's right, I said that they consider Jesus Christ to merely be the most powerful angel.