Let us speak of the sovereignty of God in purely modal terms. Calvinists hold to what I would refer to as an actualist understanding of the relation of God's soveriegnty to His will of decree. According to this view, God's decree is absolute, unconditional and extends to every scope of life. On the other hand, Arminians profess what we will call a 'possibilist' understanding of the sovereignty of God. According to this view, God's sovereignty is avowedly affirmed, but it is insisted that in His sovereignty, God chooses to allow contra-causal freedom("free will"). From this perspective, we are given the power of contrary choice and whatever one does, one genuinely could have done otherwise. To believe otherwise entails the violation of man's free will. The possibilist sees God's will of decree as contingent. In other words, God bases His decree on what we do (or what He knows we will do according to His foreknowledge), and having taken our behavior into consideration, acts accordingly. Calvinists see God's will of decree as necessary, absolute and unconditional. His decree proceeds from His will according to His counsel without respect to anything external to it.
This poses a dilemma for the 1-point Calvinist, according to whom 'eternal security' is affirmed, but doctrines like unconditional election and irresistible grace are rejected on the grounds that man's contra-causal freedom is violated. The reason is this: if regeneration guarantees election, then regenerate man lacks the free will to apostasize. Such a transformation of man's will from one that is totally and radically antagonistic to God's Person and His precepts excludes the possibility that he can fall away from the faith, as Wesleyans and classical Reformed Arminians affirm. Thus, the 1-point 'Calvinist' is doomed to inconsistency.
It's for this reason that I call them "Hotel California Calvinists": "You can check out anytime you like, but you can never leave."