Then that lawless one will be revealed whom the Lord will slay with the breath of His mouth and bring to an end by the appearance of His coming; that is, the one whose coming is in accord with the activity of Satan, with all power and signs and false wonders, and with all the deception of wickedness for those who perish, because they did not receive the love of the truth so as to be saved. For this reason God will send upon them a deluding influence so that they will believe what is false, in order that they all may be judged who did not believe the truth, but took pleasure in wickedness.
So these could have been “saved.” But according to the Calvinist doctrine of Unconditional Reprobation, how do the alleged non-elect, who have no Savior who died for them, have any opportunity “so as to be saved”? Some passages of Scripture simply don’t fit with Calvinism.
The natural implication is that these know the truth, but choose to reject it, and hence the delusion is coming. However, if understood through the lens of Calvinism, and that these have no choice of whether to receive the truth or not, then what worse thing does “strong delusion” do them, that Unconditional Reprobation hasn’t done already?
John Calvin comments: “To prevent the wicked from complaining that they are perishing innocently, and that they have been appointed to die by God’s cruelty rather than by any fault of their own, Paul shows that there are good reasons why the punishment of God is going to come upon them with such severity. It is because they have not embraced the truth which was offered to them with the proper frame of mind. Indeed, they have rejected salvation of their own accord.” (Calvin’s New Testament Commentaries: Romans and Thessalonians, p.406, emphasis mine)
But if Jesus didn’t die for them, then what exactly was being “offered to them”? As a side note, John Calvin never explicitly affirmed the doctrine of a Limited Atonement.