Atheist I know, claim they don't believe in the "supernatural", but I don't think there is anything more supernatural than nothing creating everything without a cause.
What could be more supernatural than that?
Life spontaneously emerging from inorganic material unplanned and unguided.
That seems supernatural to me.
If anything a transcendent cause seems a very natural understanding. God isn't supernatural, rather without him there is no nature at all.
Romans 1:20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:
It also completely contradicts the second law of thermodynamics. An explosion from chaos cannot create order.