Note 1 at 2 Th. 2:13: Verse 13 contains many doctrinal elements such as: thanksgiving, brotherly love, God's love for the saints, election, sanctification by the Holy Spirit, and faith in the gospel.

Paul begins this section by going from the singular to the plural and using our English word "we." This indicates that Timothy and Silas are now joining Paul in their thanksgiving for the Thessalonians.

Paul's statement about the brethren being "beloved" of the Lord brings out the fact that believers are thoroughly loved by God. It was God who had chosen them unto salvation. The Greek verb HAIREOMAI means "to take for oneself, to prefer, to choose" (Thayer).

The phrase "through sanctification of the Spirit" shows that it was the Holy Spirit who was setting apart the believers unto salvation, while "belief of the truth" shows that the object of the Thessalonians' faith was the gospel.

Note 2 at 2 Th. 2:13: Paul had just spoken some very sobering words about the fate of those who don't love the truth (vv. 11-12). Now he reassures the Thessalonians that he wasn't including them in this number of people who would be damned.