I have never had Jehovah's Witnesses come to the house, but a few months ago, Mormons knocked on the door, and they were very polite. They did ask if they could speak with me, and I had nothing else on, so said yes. We talked at the doorstep. I figured they were either JW or Mormons, but they didn't identify themselves immediately.
The first thing they asked me was if I was worried about the future, and mentioned something about God, and I thought "Ok, let's just be honest here" and I was.
I asked them why should I be worried about the future, if it's all part of God's plan? I said, wasn't it especially clear in the Book of Isaiah and the Gospel according to St. John the Apostle (among others) that we were exhorted to trust in the Lord? And that it is not our place to question the Lord's purpose, and so what was there to worry about? (I know my theology).
They seemed surprised, and just kept going on about being worried about the future, and what about all the things from Revelation. I just kept saying that the Bible is clear that it is not for us to judge and we should trust that God has a plan for us. In the end, we had to agree to disagree. I'm not bothered by it, but they didn't seem to have any clue what I was talking about. They also seemed not to know much about what's actually in the Bible except Revelation.
I wonder if they'll come back, or maybe they've decided I am a lost cause. I found it quite entertaining.
OP, if you don't want to talk to them, just say "no thanks " and close the door.