Paul makes it clear when addressing believers on the Lord Jesus Christ, that predestination is 100% truth. His words, from God, through Jesus Christ, by way of the Holy Spirit leave no room for debate.
Ephesians 1:3-14 (New King James Version)
3) Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ,
4) just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love,
5) having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will,
6) to the praise of the glory of His grace, by which He made us accepted in the Beloved.
7) In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace
8) which He made to abound toward us in all wisdom and prudence,
9) having made known to us the mystery of His will, according to His good pleasure which He purposed in Himself,
10) that in the dispensation of the fullness of the times He might gather together in one all things in Christ, both which are in heaven and which are on earth?in Him.
11) In Him also we have obtained an inheritance, being predestined according to the purpose of Him who works all things according to the counsel of His will,
12) that we who first trusted in Christ should be to the praise of His glory.
13) In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise,
14) who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory.
This was part of the first portion of Paul’s letter to “the saints who are in Ephesus, and faithful in Christ Jesus”. Without question, Paul after giving praise and glory to “God our Father and the Lord Jesus Christ”, tells the how their calling and selection was “chosen”, “predestined”, before the foundation of the world. For God’s own glory.
It was not a generic letter to the area, but specifically to the saints there. All are not called to the Lord, saints who trust in the Lord Jesus are.
The saints were chosen by God before even being born. Praise God! If you know Jesus as your Lord and Savior, it is because He knew you first and called you to Himself.
When Jesus Christ, the only begotten Son of God prayed to His Father, He said:
John 17:24 (New King James Version)
24) ?Father, I desire that they also whom You gave Me may be with Me where I am, that they may behold My glory which You have given Me; for You loved Me before the foundation of the world.
Related post: The Fact I Can No Longer Deny, Predestination is Real!