The Cosmological Argument but who caused the 'first' cause?

  The he Cosmological Argument i.e. something caused the Universe to exist, and this First Cause is what we call God. It has been used by various theologians and philosophers over the centuries, from the ancient Greeks Plato and Aristotle to the medieval (e.g., St. Thomas Aquinas). The cosmological argument requires a self-originated motion to cause action. However the argument falters when the proponents of a first cause (God) fall back on the theory that the First Cause is exempt from the question 'who then caused the first cause?' God is outside our concept of time, cause and motion. Yet, the argument persists, if he is outside it how can s/he intervene?