I would never open the door for any reason. I would be on the other side of the door with a firearm while my wife was dialing 911. I would warn the person that he had the wrong address and should move on while he can. Once he starts using his body against the door, he becomes a threat and receives no more warnings. If the door is breached, I fire until the threat is stopped.
No one will ever force their way into my home without facing deadly force. I've run over this many times in my mind and I have no doubt.
G26, G19, Saiga 5.45x39
"We, the people are rightful masters of both Congress and the courts -- not to overthrow the Constitution, but to overthrow the men who pervert the Constitution."