Hmm... pretty much any pro-god argument really... but this one takes the cake...
"Well, God was well within his rights to drown the world for 40 days and 40 nights because everyone was evil back then except for Noah and his family."
Me: "Erm... how do you know they were all evil?"
Them: "Because the Bible said so."
Me: "The Bible... that you believe God ghost-wrote?"
Them: "Yes."
Me (facepalming at this point) : "So they were evil because God said they were?"
Them: "Er..."
Me: "So all of the children and their grandmothers were all evil?"
Them: "Umm..."
Me: "And therefore deserved to burn and choke and die in hell for eternity?"
Them: "Well... God works in mysterious ways."
Me: "Cruel ways more like. And you worship this git because...?"
Them: "I was raised to!"
Me: "Right..." (walks away in disgust)
"Well, God was well within his rights to drown the world for 40 days and 40 nights because everyone was evil back then except for Noah and his family."
Me: "Erm... how do you know they were all evil?"
Them: "Because the Bible said so."
Me: "The Bible... that you believe God ghost-wrote?"
Them: "Yes."
Me (facepalming at this point) : "So they were evil because God said they were?"
Them: "Er..."
Me: "So all of the children and their grandmothers were all evil?"
Them: "Umm..."
Me: "And therefore deserved to burn and choke and die in hell for eternity?"
Them: "Well... God works in mysterious ways."
Me: "Cruel ways more like. And you worship this git because...?"
Them: "I was raised to!"
Me: "Right..." (walks away in disgust)