God from the beginning chose you for salvation -- 2 Thessalonians 2:13
Out of context, this verse seems very unfair towards people that God might not have chosen for salvation.
But if you carefully study the full chapter of 2 Thessalonians 2 you will notice that Paul was addressing the first believers (translated as “first fruits” or even left out by some translations). In other words, God choose the first disciples or congregation of believers for a very specific purpose in that time.
Now, if you look at the prior verses in 2 Thessalonians 2:1-12 talks about a great deception that was ruling at that time and it was important for God to choose the correct people for this specific calling.
Paul is thankful that the believers did not give into the great deception.
In Romans 1:16, the same Paul writes that everyone who believes can be saved.