it could not be an effect in an infinite series of causes and effects
must be caused by something outside of space and time
stage 2
all contingent beings depend for their existence on an uncaused being
the cosmos is a contingent being therefore the cosmos depends for its existence on some uncaused being
pointed out that it is impossible that the world has existed for an infinite amount of time because that would mean it an infinte number of years has gone by which is self contradictory there must have been a point where the world had a beginning.