I get some version of that rather often, typically from liberal believers. Anyway, here was my response:
The problem is that they are rather specious questions. Where is the scientific experiment conducted by Leprechaun-deniers that definitively proved that "There are no Leprechauns?” How did they define the Leprechaun whom they state doesn't exist? (I quoted the article, substituting Leprechaun for God)
I do not lose any sleep over not answering such questions. If someone wants to feel they scored points on me when I don’t, enjoy. I have no motivation to spend the effort to believe in Leprechauns when there is no reason to. I don’t believe in Leprechauns… but if I saw one, I would be happy to have been wrong and I think the event would be amazing. It is the same with deities.
“To speak of God properly…” Mr. Hart shows he is playing with loaded dice from his first statement. In this sense, he is no different from the varied other theists I have encountered in my life. From the Hell, Fire, and Brimstone preacher, to the pentecostal healer, to the prosperity pastor… they all want to tell me how to view God “properly”. Even believers whom I respect such as Borg, Spong, and Rohr have their own take on viewing God “properly”. In the end, I don’t think these people are telling me about God, they are telling me about themselves… but that is another thread.
I once had an ex-Mormon friend of mine who said, “Mormonism really is a beautiful belief structure… but you have to stay within their box of thinking to make it work.” Many of the arguments made for theism, or against atheism, have this kind of set-up… you have to accept certain premises in order for the argument to work. If someone tells me – “Here is what Atheism is!” and it doesn’t line up with how I think about my atheism, all of their arguments thereafter are meaningless. (I think the reverse is also true, so I rarely go after someone on their theism and stick to my problems with harmful dogma.)
It is similar to when my 2nd-grade students want to tell me a joke/riddle that starts with a question. When I answer in a way they had not anticipated, they start over and instruct me on how to answer “properly”. In order for the joke/riddle to work, I have to give the right response. When it is over, they are gleeful with their joke/riddle telling skills and I play along, but it is a contrivance.
Any argument where I have to accept a very narrow (or very vague) premise from the get-go in order for the argument to work is a contrivance. Such arguments work for the already convinced, but to those outside the acceptance of the foundational premise, it simply doesn’t sell.