"And we know that all things work together for good to those who love God, to those who are the called according to His purpose. For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren. Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified." (Romans 8:28-30).
The foreknowledge of God is a key factor when discussing the sovereignty of God and responsibility of man in salvation. Generally, Calvinists hate the mere mention of it, but as it is in scripture, we simply do not have the luxury of ignoring it.
God is omniscient. That means He knows all things. Not just all things that are, but all things that will be, and all things that could be. We see examples of Him flexing this ability in scripture. I, personally, am most fond of using Matthew 11:21-23: ""Woe to you, Chorazin! Woe to you, Bethsaida! For if the mighty works which were done in you had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes. But I say to you, it will be more tolerable for Tyre and Sidon in the day of judgment than for you. And you, Capernaum, who are exalted to heaven, will be brought down to Hades; for if the mighty works which were done in you had been done in Sodom, it would have remained until this day."
In His condemnation of Bethsaida, Chorazin, and Capernaum, Jesus shows both God's foreknowledge (He knew what would happen if Jesus had done His miracles in Tyre, Sidon, and Sodom) and His sovereignty (in spite of His knowledge, He still chose not to do His works there).
Anyone other than a Calvinist would see the foreknowledge of God in Romans 8:29 and suggest that before God even created the heavens and the Earth, He knew who would be saved, and how. The only response I have seen a Calvinist give to this reasoning is that if God has to look through time and learn things, He is not truly omniscient. But while this is a valid criticism of, for example, Open Theism, it is not a valid response to the argument itself, as no one other than Open Theists would say God didn't know the future until He looked through time. Rather, God knows, and has always known, what would and could happen.
We see, then, that non-Calvinist philosophies, other than Open Theism, are not a challenge to God's omniscience. But Calvinism is actually a challenge to His omnipotence. See, we can ask the Calvinist if God created a free agent, would He know what that free agent would do? The answer to that is an absolute "yes". No Calvinist, without flat out denying that God is omniscient, can disagree with this. But the next question becomes "could God create that free agent?"
Most Christians would find this to be a silly question. Not only could God create free agents, He does so on a daily basis. Every conscious creature has free will. I have free will. You have free will. My dog has free will. God has full control over what He creates; nothing is impossible for God. Giving a barren old woman a child? Not a problem for God. Giving a virgin woman a child? Easy for God. Making propitiation for the sins of the whole world through the death and resurrection of the aforementioned Son of a virgin woman? The entire reason we are having this discussion is precisely because such an act was carried out by God. God, being sovereign over His creation, can create any thing that is a thing.
Now, that is a vital qualification. There are things which do not exist, such as a pegasus, or a minotaur, that are things. Although there is currently no such thing as a minotaur, minotaurs are not inherently illogical, and God can therefore make there become such a thing as a minotaur. However, a round triangle is inherently illogical, simply because it is a contradiction in terms. If it is round, it is not a triangle. If it is a triangle, it is not round. Therefore, a round triangle is not a "thing", and so God cannot make it.
Statements like "God cannot...", to the untrained ear, may seem close to blasphemy, but the Bible actually does tell us there are some things God cannot do. "Thus God, determining to show more abundantly to the heirs of promise the immutability of His counsel, confirmed it by an oath, that by two immutable things, in which it is impossible for God to lie, we might have strong consolation, who have fled for refuge to lay hold of the hope set before us." (Hebrews 6:17-18). "Paul, a bondservant of God and an apostle of Jesus Christ, according to the faith of God’s elect and the acknowledgment of the truth which accords with godliness, in hope of eternal life which God, who cannot lie, promised before time began, but has in due time manifested His word through preaching, which was committed to me according to the commandment of God our Savior;" (Titus 1:1-3). "If we are faithless, He remains faithful; He cannot deny Himself." (2 Timothy 2:13).
The key to understanding God's sovereignty, then, is to simply say, rather than God being completely and utterly limitless, the only limit on God is Himself. There is nothing higher than God, but that includes God Himself. Therefore, if something is not Godly, God cannot do it. This is why God cannot lie, even though lying is a relatively simple thing to do. Satan can lie quite effectively. We can lie for hours on end. But God cannot, because lying is detestable to Him.
In the same way, God's inability to "deny Himself" can be adequately understood as the inability to make a true contradiction. If God makes a triangle, God makes a triangle, and so making it round would, in effect, be denying Himself. In the same way, then, God is absolutely able to make free agents (and to know what they will do), but He is absolutely incapable of making free agents without freedom. This is not a denial that God is sovereign, but an affirmation that God cannot deny Himself.
But the Calvinist position that a truly free agent would go against God's sovereignty is actually saying God is not free to create a perfectly rational thing if He wants. Furthermore, you are saying God does what He says in scripture He cannot do. How? Simply because scripture repeatedly affirms that evil does not come from God, but from the desire of the evildoer. James 1:13-15 is the best example: "Let no one say when he is tempted, “I am tempted by God”; for God cannot be tempted by evil, nor does He Himself tempt anyone. But each one is tempted when he is drawn away by his own desires and enticed. Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death."
God cannot be tempted, and does not tempt anyone. Therefore, when we sin, we can only say we sin because we wanted to. We could have chosen not to. In fact, for various reasons or others, we often do. Just as we may also choose to do good, as once again we often do.
So then how is God still sovereign, if we have free will? Well, a fact Calvinists often forget is that He can fulfill His plans without our consent or our help... We see this multiple times in scripture. "For if you remain completely silent at this time, relief and deliverance will arise for the Jews from another place, but you and your father’s house will perish. Yet who knows whether you have come to the kingdom for such a time as this?”" (Esther 4:14). "and do not think to say to yourselves, ‘We have Abraham as our father.’ For I say to you that God is able to raise up children to Abraham from these stones." (Matthew 3:9). "But He answered and said to them, “I tell you that if these should keep silent, the stones would immediately cry out.”" Nothing, be it our rebellion or cooperation, would thwart God. If we do something against His will, He thwarts us, we lose, He wins. If we do what He wills, He is glorified, He wins, and by His grace, we become a part of that victory.
To really drive this point home, we can actually use one of Calvinism's favorite analogies: The sovereign potter. In Jeremiah 18:1-6, we read "The word which came to Jeremiah from the Lord, saying: “Arise and go down to the potter’s house, and there I will cause you to hear My words.” Then I went down to the potter’s house, and there he was, making something at the wheel. And the vessel that he made of clay was marred in the hand of the potter; so he made it again into another vessel, as it seemed good to the potter to make. Then the word of the Lord came to me, saying: “O house of Israel, can I not do with you as this potter?” says the Lord. “Look, as the clay is in the potter’s hand, so are you in My hand, O house of Israel!"
Note that as the potter is making one thing with the clay, it becomes marred in his hand, and so he makes another vessel. And so God says "as the clay is in the potter's hand, so are you in My hand". So what does that tell us? It tells us that God is sovereign even over "clay" that will not conform to His original design.
A Calvinist might argue back that this still means God is not sovereign, since His original design would therefore never come about. But to that I say, actually, He actually planned for that to happen.
See, God's foreknowledge changes the game so radically that we are now free to interpret Romans 9, a Calvinist's favorite chapter, without a Calvinist lens. "You will say to me then, “Why does He still find fault? For who has resisted His will?” But indeed, O man, who are you to reply against God? Will the thing formed say to him who formed it, “Why have you made me like this?” Does not the potter have power over the clay, from the same lump to make one vessel for honor and another for dishonor? What if God, wanting to show His wrath and to make His power known, endured with much longsuffering the vessels of wrath prepared for destruction, and that He might make known the riches of His glory on the vessels of mercy, which He had prepared beforehand for glory, even us whom He called, not of the Jews only, but also of the Gentiles?" (Romans 9:19-24).
With a Calvinist lens, that passage is usually interpreted as God intentionally making certain individuals for the sole purpose of going to Hell. They sinned because the God who cannot tempt anyone to evil (James 1:13) wanted them to sin, and they rejected His command to repent because He who wants all to be saved and come to the knowledge of the truth (1 Timothy 2:3-4) didn't want them to be saved and come to the knowledge of the truth. The God who takes no pleasure in the death of the wicked (Ezekiel 33:11) takes great pleasure in making them wicked, just so He may cast them into the lake of fire.
But without a Calvinist lens, what we actually see that God, knowing full well (Romans 8:29) everything these people would ever do under any circumstance He chose to put them in, nevertheless chose to put them in the circumstances in which, though they could do good (Jeremiah 26:3), instead chose evil, which He had every right to do (Romans 9:20-21). Thus, instead of condemning them because He wanted to, they became marred in His hand (Jeremiah 18:4), and so He "endured them with longsuffering" (Romans 9:22), because knowing all this, He instead used them to show His attributes; His wrath, His mercy, His glory, which simply could not be shown if these vessels did not exist.
What's more is that God can orchestrate all of this without tempting a single person to sin. See, there are limits to free will, and even ways that finite beings such as ourselves can use to influence others. For one thing, we cannot act on information we do not know. This is why we can trick each other into freely doing things we otherwise would not. I, for example, can use clickbaity titles, like "Why don't Calvinists believe God is sovereign?", both to make some people read this article, and to trick those who will refuse the article into proving they didn't read the article by answering the headline. If I, as a simple man, can do that, why is it illogical to think God would also have the ability to influence our free will?
Furthermore, there are some things free will doesn't cover. I may choose how I celebrate my birthday, but I cannot choose when my birthday is. Who chooses that? God. God could have made me a black woman born in Africa in 300 B.C. if He wanted to, and that would drastically alter my free choices. He could have made me the exact same person, but a year older, or a year younger, and that tiny little difference would change my whole life, all without putting a dent in my free will.
Once again, we see this with Sodom and Gomorrah. Jesus tells us what would happen if He did His works there. But He chose not to. Sodom deserved condemnation, they did not deserve His mercy, and so in this case, God chose not to do the thing that would have made them repent, all so that we would see His mercy and His wrath.
When we put all of this together, we see that Calvinism is a weak theology simply because it fails to account for a significant amount of scripture, and that when those scriptures are factored in, the Calvinist response is that this means God is not sovereign. In reality, however, it is the Calvinist who must deny that either God can know what would happen if He created free agents, or that He can create those free agents in the first place. Therefore, while all views must naturally acknowledge that there is at least one thing God cannot do, the Calvinist must place a limit on God that is not justifiable by any attribute scripture tells us God has. For this reason, I reject Calvinism because I believe God is 100% sovereign, even over the free agents He has created.