In answer to Why? Cause Deist want to and don't really have to answer to anyone for those beliefs nor should they have to. Any more than an Atheist should have to answer to anyone for their beliefs. Nor should Christians, Hindi, Buddist, Druids, Wiccans, Islam, Jews or people from the Church of the Divine Spegetti Monster with his noodly appendages. It is all about personal choice and that personal choice is valid as long as they are willing to respect the personal choices of others.
OR is just a tool for simplifying logical arguments. It's not a measurement or an observation, so it certainly could not be used as "evidence against theology". I was pointing out that tools of logic can be twisted especially when applied to non-scientific applications such as theology.