#1 Without Adam there is no fall, no original sin and no need for a substitutionary atonement.
A clear and succinct explanation of why the doctrines of the atonement and original sin do not make any logical sense even within themselves:
For those who say that this proves that Adam must have existed, please think on this:
If I told you I had fairies at the bottom of my garden you would expect me to provide objective evidence for my claim. The same burden of proof is required for any religious argument such as the existence of Adam. Simply using one source (the bible) to validate itself is not good enough.