The First to the Corinthians: Titles like this were apparently not part of the original text. Ancient manuscripts show that they were added later, doubtless to make it easier to identify the letters. The papyrus codex known as P⁴⁶ shows that scribes identified Bible books by titles. That codex is the earliest known collection of Paul’s letters, often dated to about the year 200 C.E. It contains nine of his letters. At the beginning of Paul’s first inspired letter to the Corinthians, this codex has a title that reads Pros Ko·rinʹthi·ous A (“Toward [or, “To”] Corinthians 1”). (See Media Gallery, “Paul’s First Letter to the Corinthians.”) Other early manuscripts, such as Codex Vaticanus and Codex Sinaiticus of the fourth century C.E., contain the same title. In these manuscripts, the title appears both at the beginning of the letter and at the end.

The Second to the Thessalonians: Titles such as this were apparently not part of the original text. Ancient manuscripts show that the titles were added later, doubtless to make it easier to identify the books.​—See study note on 1Co Title.

Silvanus: See study note on 2Co 1:19.

to the congregation of the Thessalonians: Like Paul’s first letter to the Thessalonians, this letter is addressed “to the congregation” in general. This differs from his letters to Timothy or Titus, which were addressed to individual overseers, and from the letter to the Philippians, which specifically mentions the congregation overseers and the ministerial servants.​—Php 1:1.

is growing exceedingly: At the beginning of his first letter to the Thessalonians, Paul mentions their faith and love. (1Th 1:3) Here he commends them because of the remarkable growth of these qualities in them. The term he uses (hy·pe·rau·xaʹno) is related to a word that was often used regarding the growth of plants. (Mt 6:28; Lu 13:19) Paul adds the Greek prefix hy·perʹ (meaning “over; beyond”) for emphasis. (Compare Eph 3:20, “superabundantly beyond.”) So here the expression could literally be rendered “is having supergrowth.”​—Kingdom Interlinear.

hardships: Or “tribulations.”​—See study note on 2Co 1:4.

the revelation: Or “the uncovering; the disclosure.” The Greek term a·po·kaʹly·psis is here used in the expression “the revelation of the Lord Jesus.” He will be revealed as King and Judge, empowered to reward and to punish. At the time of his “revelation,” he will reward his faithful followers, who have suffered tribulation, and he will execute vengeance on the ungodly.

in a flaming fire: The Scriptures often use “fire” in a figurative sense, as in this verse. In Bible times, fire was the most thorough means of destruction. (De 13:16; Jos 6:24) On occasion, Jesus used the term “fire” in an illustrative way to denote the complete destruction of the wicked.​—Mt 13:40-42, 49, 50; compare Isa 66:15, 24; Mt 25:41.

vengeance: That is, divine vengeance and judgment. Paul says that “it is righteous on God’s part to repay tribulation to those who make tribulation” for the Christians. (2Th 1:6) The Greek word rendered “vengeance” (ek·diʹke·sis) literally means “from justice,” suggesting that the action represents justice achieved. It has also been rendered “meting out justice” or simply “justice.” (Lu 18:7, 8; 21:22 and study note) The Bible shows that God is ultimately responsible for bringing “vengeance” that will result in true justice. (De 32:35, 43; Ps 94:1; Ro 12:19; Heb 10:30) For the vengeance that Paul describes here, God has appointed the Lord Jesus Christ as Chief Executioner.

those who do not know God: Paul refers to those who willfully decide that they will not develop a relationship with Jehovah and become his friends. In contrast, those who “know God” do more than acknowledge that he exists; they have more than superficial knowledge of him. They take steps to develop a close friendship with him; they know his likes and dislikes. They love him and live by his standards. (1Jo 2:3, 4; 4:8) Those who truly know God have the honor of being “known by him” (1Co 8:3), which means having his approval.​—See study notes on Joh 17:3; Ga 4:9.

the good news about our Lord Jesus: This expression includes all that Jesus taught, as found in God’s Word. This good news is the basis on which all mankind will be judged. Those who accept and obey the good news will gain salvation; those who “do not obey the good news” will bring destruction on themselves.

everlasting destruction: The Bible indicates that some people will suffer everlasting destruction. For example, Jesus said that those who blaspheme the holy spirit are “guilty of everlasting sin” and will not be forgiven, “no, not in this system of things nor in that to come.” (Mr 3:28, 29; Mt 12:32) This apparently includes Judas, whom Jesus called “the son of destruction.” (Joh 17:12 and study note) Judas’ deliberate betrayal of the Son of God made him subject to everlasting destruction. Here Paul states that those who by choice “do not know God and those who do not obey the good news about our Lord Jesus” will experience “everlasting destruction.”​—2Th 1:8.

from before the Lord: Lit., “from the face of the Lord.” Although the words at 2Th 1:9 may allude to what is expressed at Isa 2:10, 19, 21, this is not a direct quotation from the Hebrew Scriptures. “The Lord” could here be referring either to Jehovah God or to Jesus. In a case like this, the New World Bible Translation Committee retained the rendering “Lord” so as not to overstep the bounds of a translator.​—See App. C1; compare study note on Ro 10:12.