One of the problems I have with analytical philosophy is the tendency to fail to distinguish between logical and metaphysical necessity. Or, more precisely, it is to invert the priority of being and logic.
The Maverick Philosopher wrote a post the necessity of God that exemplifies this tendency.
The MP refers to "philosophers in the tradition of Anselm and Aquinas" who define God as a necessary being, and he takes them both to mean the same thing - logical necessity. But St. Thomas rejected Anselm's Ontological Argument precisely because he understood the necessity of God to be a metaphysical necessity, not a logical necessity.
Logical necessity refers to the relationships of the terms of propositions to each other. Thus a "logically possible world" is one that involves no propositional self-contradiction. No logically possible world can contain married bachelors, because bachelors are by definition not married. But there is no self-contradiction in supposing that a body can be at two different places at the same time; for example, that you could be in Boston and Binghamton simultaneously. That it is not possible for you to be in both Boston and Binghamton at the same time is a consequence of your incarnate nature; it is the nature of bodies as such that they occupy one and only one place. It is a metaphysical necessity. Thus "John is in Binghamton and in Boston" is logically possible, but metaphysically impossible.
When Thomists discuss the necessity of God, they mean that God is metaphysically necessary, not logically necessary. There is no logical contradiction involved in denying the existence of God. But it is to assert a metaphysical impossibility. The Thomistic arguments for God are all different ways of revealing this metaphysical necessity.