Whoever formulated the "necessary being" argument must have really tried hard, as I have never heard an argument more shallow, blatantly dishonest, and hateful of reason. Instead of going to all the trouble of creating this "unnecessary being", why not save a step and accept the Reality of Nature? Do you really hate Nature so much as to wish to step beyond and apart from Her? The "necessary being" argument is necessary only for the ego in its unending battle against reality.
Christians say that a "creative agency" is necessary to explain why this particular Universe came about instead of any one of infinite possible Universes. Yes, a creative agency is indeed required, and that creative agency is their own foolish brains! Contingency ensures there is no such thing as chance. Only one thing is ever possible - that which happens. "Coincidences" are therefore impossible, though there can be ignorance about the possible.