As Warren, Alistair and I met at 2pm at the Redcliffe Jetty, we firstly prayed and then made our way down the Jetty giving gospel tracts to everyone we met. We had some good one-2-one conversations, with the gospel being clearly proclaimed.
One conversation I had was with an elderly fellow, who was a deist - someone who believes God just made the world and has never interacted with it. This man was very versed in psychology, and loved to talk about it. When I asked him whether he thought there was a God, he quoted some psychologist who doesn't believe there is a God, but rather knows there is a God. However, I pointed out that psychology just deals with the subjective, so his 'knowing' that there is a God can only be based on some feeling/experience that he has had. I said we can objectively know there is a God because of the things that have been made (Romans 1:20). He agreed, but he did not think God has intervened or interacted in any way with this world.
So I asked him if he thought God is just. He said yes. So I pointed out that for God to be just he cannot turn a blind eye to the things that are happening on this Earth, but rather he must punish the people that do sinful things. He said, "We punish ourselves". So I responded, "No we don't. Some people may, but the most don't. We don't like getting punished. That is the exact reason why a criminal will not usually turn himself in to the police."
So then I talked about the judgment to come after we die where God will judge us on everything we have done. This lead onto the gospel message and what someone must do to be saved. However, through his psychology study, he had learnt that humans are inherently good. So I asked him, "Do we have to teach our children to disobey? No, of course not. Thus that shows that we are all inherently evil from our birth." I let him know that psychology usually goes completely contrary to what the Bible says because it tries to teach people that they are good. But the Bible says we are not, and the objective evidence seems to point that way as well.