You can probably guess what my answer is going to be...
I've talked to Yahweh, and Yahweh has talked to me. How do I know? Because it cut over the top of everything that was happening at that present moment, but God did not come to me in person physically nor can I think of any event recorded that he has except through Yeshua (Jesus).
John 10:27
My sheep listen to my voice; I know them, and they follow me.
This individual could of been talking to anyone, even Satan himself given by the answers that this 'man' was giving to the Atheists questions.
2 Corinthians 11:14
And no wonder, for Satan himself masquerades as an angel of light.
If this man said to me if he were god, I would test him as instructed by his word in the bible.
1 John 4:1
Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world.
2 Corinthians 4:4
The god of this age has blinded the minds of unbelievers, so that they cannot see the light of the gospel that displays the glory of Christ, who is the image of God.
Coincidence? I think not.