Welcome back brother! Hope you're doing better! As for the athiests...I don't think they stray far from the TOE forum.
As for your challenge and point of proving God, from a believer's perspective, they seek a sign. The Jews of Jesus day asked for the same thing, and He told them that if they didn't believe the Moses and the Prophets, how then would they believe Him. I find it interesting that He says "Moses." Why? Because Moses wrote the first five books of the bible,
including the creation account! He says effectively in my paraphrase, "I've given you the truth already. Do you believe what I've given you?" They obviously, do not. And that is a sad position to be in to be sure.
As for the free will aspect...I tend to believe that God has given us the choice to obey or disobey. I also believe (as scripture repeatedly shows) that our sovereign God can and does limit those choices. How would God then make it possible for us to know Him? Through revelation, both physical and spiritual. Physical in the creation, spiritual through the hearing of His word. I believe that He sovereignly gives us the opportunity to believe - to actively put our faith in the word we hear - to obey His call.
I hopefully didn't ruin this for anyone for whom it was intended. If so...maybe repost it in the TOE forum?
Anyways, I look forward to reading your posts, and am glad to hear from you again my brother!