2nd Thessalonians 2:13-14 (see also 1st Thessalonians 5:9)
But we should always give thanks to God for you, brethren beloved by the Lord, because God has chosen you from the beginning for salvation through sanctification by the Spirit and faith in the truth. It was for this He called you through our gospel, that you may gain the glory of our Lord Jesus Christ.
John Calvin comments: “Paul here treats election in no other sense and for no other end than elsewhere, when he gives thanks to God for having from the beginning elected the Thessalonians to salvation (II Thes 2:13), thus distinguishing a small part from an ungodly magnitude.” (Concerning the Eternal Predestination of God, p.159, emphasis mine)
Some Calvinists acknowledge that eternity is not the focus of the matter:
Calvinist, George Gunn, comments: “In light of these findings, 2 Thessalonians 2:13 may be paraphrased as follows: ‘We ought to thank God always for you, brothers, beloved by the Lord, because God chose you, a firstfruit of the European mission, for deliverance by means of the rapture from the judgments that shall befall those who follow the man of lawlessness in the Tribulation Period. God made this choice by setting you who believe the truth apart from those who will believe the antichrist’s lie.’” (2 Thessalonians 2:13, A Rapture Passage?)
Calvinist, William MacDonald, comments: “From the beginning. This has two possible readings. First, it may mean that God’s choice was made before the foundation of the world (Eph. 1:4). Second, the expression may also be read ‘as first fruits,’ indicating that the Thessalonians, saved so early in the Christian dispensation, were chosen by God to be among the first of a great harvest of redeemed souls.” (Believer’s Bible Commentary, p.2056, emphasis mine)
John Calvin comments on a First-Fruits interpretation: “Some interpret this to mean that they had been among the first to be called. But this is foreign to Paul’s meaning, and is inappropriate to the context. He is not simply delivering from fear a few individuals who were brought to Christ at the very beginning of the Gospel; this consolation has reference to all whom God has chosen without exception. In saying from the beginning, therefore, he means that there is no danger that Satan should reverse their salvation, which is based on the eternal election of God, however chaotic an upheaval there should be. ‘However universal the disorder which Satan may cause in the world, your salvation was assured before the creation of the world.’ This, then, is the true haven of our security, that God, who has chosen us of old, will rescue us from all the distresses that threaten us. We are elected to salvation; we shall therefore be safe from destruction. But since it is not our business to penetrate into the secret counsel of God, there to seek the assurance of our salvation, he designates the signs or tokens of our election, which should give us sufficient confidence in it.” (Calvin’s New Testament Commentaries: Romans and Thessalonians, p.409, emphasis mine)
John Calvin not only imports “before” into the text at v.13, but also invents his own context, since the focus of the context never raises the matter of assurance of the salvation of their soul, but already “proudly” assumes it (2nd Thessalonians 1:3-4), in affirming that they “believed.” (2nd Thessalonians 1:10). The context of the salvation at hand is in regard to deliverance from the end-time wrath to come. The parallel passage of 1st Thessalonians 5:9 states: “For God has not destined us for wrath, but for obtaining salvation through our Lord Jesus Christ.” Paul provides repeated encouragement to remain steadfast, in light of present persecutions, afflictions and suffering (1st Thessalonians 1:4-5), in order to be “considered worthy of the kingdom of God” (2nd Thessalonians 1:5), so that “our God will count you worthy of your calling” (2nd Thessalonians 1:11) and “that the name of our Lord Jesus will be glorified in you, and you in Him.” (2nd Thessalonians 1:12)
Calvinist, James White, comments: “The text shows that the work of the Spirit and our faith in God’s truth are the result of that eternal choice.” (Debating Calvinism, p.110, emphasis mine)
No, the text does not say that they were chosen to believe.
The back-drop is that the Thessalonians mistakenly thought that they were in the Tribulation (2nd Thessalonians 2:1-10), and Paul clarifies that that was not the case, and states that first, the Hinderer must be removed, which some infer as either being Christians or the Holy Spirit, but the point is that they were not in the Tribulation, and moreover, that it was not the purpose of the Tribulation to test the Church, but to test the world that had rejected the Gospel, and warmly received the “deluding influence” instead. (2nd Thessalonians 2:11)
James McCarthy sums it up this way: “It was part of God’s original plan to deliver the body of Christ from end time evil and the great tribulation.” (2 Thessalonians 2:13, Did God Choose Whom He Would Save?)
From the context, it is apparent that the intended meaning of “salvation” at 2nd Thessalonians 2:13 meant a deliverance from the wrath to come, for which God had not destined Christians.