Imagine you are being tried for a crime you did not commit. There is no physical evidence to convict you. No D.N.A. that places you at the crime. No videotape evidence , no fingerprints , no fiber evidence. You were at home sound asleep at the time of the crime but you cannot prove it. The prosecutor uses only an argument that asserts a rational for why you could have committed this crime. It is only one possible scenario and the prosecutions argument is valid but untrue. Your only defense is to counter with another valid argument and start a debate. You would hope that our criminal justice system and a jury of twelve peers would see through this facade and refuse to convict based on lack of evidence. A rational jury would fail to be convinced of your guilt beyond a reasonable doubt since reason requires evidence.
This is my analogy for most of the debates I see online between theists , philosophers , and atheists.