13 ¶ But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth: 14 Whereunto he called you by our gospel, to the obtaining of the glory of our Lord Jesus Christ.
Here is a set of verses that can appear to be a support for Calvinism. Indeed, you are chosen to become something after you’ve been saved. Paul is thanking God that He has chosen the Thessalonians to salvation.
But, God’s choosing of them is based on His foreknowledge, not any intention to create people who had no chance of being saved.
1Peter 1:2 Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied.
These verses show two things at work in the act of salvation. One is the movement of the Holy Spirit in the would-be believer’s life and the second is the belief generated from within the believer.
After that there is a calling by the gospel delivered by Paul and then the glory given to the believer by the Lord Jesus Christ.
God knew you were going to be saved, to believe in Him, and to have faith given to you by Him before the foundation of this world. In this verse in Ephesians note that we are “in him,” when we are chosen.
Ephesians 1:4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
No one comes to Christ by argument. No one comes to Christ by debate. No one comes to Christ that God didn’t foresee would come to Christ, that weren’t drawn by the Holy Spirit, and believed before they were given faith. Belief is the understanding and acknowledgement that the chair will hold your weight while faith is the ability to trust the chair enough to sit in it. You have the capacity within you to believe, but faith comes from God.
Jesus lays out an important point about this here.
John 6:44 No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.
Paul speaks about belief and faith.
Romans 3:22 Even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe: for there is no difference:
Galatians 3:22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.
God gives you the means by which to please Him.
Hebrews 11:6 But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.
Ephesians 2:8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
These two events, the belief and the giving of faith, happen at once in our timeframe.
Romans 10:9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
Paul has been thankful because he has been blessed by being a part of the salvation of people who are now beloved of the Lord.
Romans 1:7 To all that be in Rome, beloved of God, called to be saints: Grace to you and peace from God our Father, and the Lord Jesus Christ.
Christ has made us a part of that beloved assembly.
Ephesians 1:6 To the praise of the glory of his grace, wherein he hath made us accepted in the beloved.
Jesus is called beloved of God.
Matthew 3:17 And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased.
The apostle, John, who some commentators say was probably a teenager during Christ’s ministry, was particularly loved by Christ as John wrote, and, as a result, is a considered to be the church in typology.
John 13:23 Now there was leaning on Jesus’ bosom one of his disciples, whom Jesus loved.
John 20:2 Then she runneth, and cometh to Simon Peter, and to the other disciple, whom Jesus loved, and saith unto them, They have taken away the Lord out of the sepulchre, and we know not where they have laid him.
John 21:7 Therefore that disciple whom Jesus loved saith unto Peter, It is the Lord. Now when Simon Peter heard that it was the Lord, he girt his fisher’s coat unto him, (for he was naked,) and did cast himself into the sea.
John 21:20 Then Peter, turning about, seeth the disciple whom Jesus loved following; which also leaned on his breast at supper, and said, Lord, which is he that betrayeth thee?
Which is why, when John is forcibly removed to heaven in chapter 4 of the Book of Revelation, commentators view it as a type of the church being translated or raptured. This is also because the church is no more mentioned in that book afterwards as being on earth.