2:19

the solid foundation of God: Paul does not specify what this “solid foundation” refers to, but in his other letters, he uses the term “foundation” to emphasize stability and trustworthiness. For example, he compares the role that Jesus plays in Jehovah’s purpose to a foundation. (1Co 3:11) At Eph 2:20, he speaks of “the foundation of the apostles and prophets.” And he describes the Christian congregation in similar terms. (See study note on 1Ti 3:15; see also Heb 6:1.) In the two preceding verses (2Ti 2:17, 18), Paul urges Timothy to resist apostate teachings. To reassure Timothy that Jehovah’s ways, activities, and qualities are always dependable and enduring, the apostle uses the expression “the solid foundation of God remains standing.”​—Ps 33:11; Mal 3:6; Jas 1:17.

having this seal: A seal could refer to the impression made by a seal or to an inscription indicating ownership or authenticity. (See Glossary, “Seal.”) It was not uncommon for a foundation or another part of a building to bear an inscription identifying its builder, its owner, or its purpose. (Compare study notes on 2Co 1:22; Eph 1:13.) The book of Revelation describes foundation stones that were inscribed with the names of the apostles. (Re 21:14) “This seal” that Paul here mentions features two important statements, as explained in the following study notes.

Jehovah: Paul here quotes Nu 16:5 (according to the Septuagint), where Moses told Korah and his supporters that Jehovah “knows those who are his.” The original Hebrew text uses the divine name, represented by four Hebrew consonants (transliterated YHWH), and the name Jehovah is therefore appropriately used in the main text of this translation.​—See App. C1 and C2.

“Jehovah knows those who belong to him”: Quoting Nu 16:5, Paul apparently uses the account about the rebellion of Korah, Dathan, and Abiram to assure Timothy that Jehovah is aware of those who rebel against Him. He can and will counteract their wickedness. Jehovah was not going to allow first-century apostates to thwart his purpose any more than he allowed Korah and his accomplices to do so centuries earlier. However, as Moses said, Jehovah recognizes those who are faithful to Him. He knows them intimately and expresses his approval of them.​—See study notes on Ga 4:9.

“Let everyone calling on the name of Jehovah renounce unrighteousness”: Paul’s wording suggests that this statement is a quote. Yet, no text in the Hebrew Scriptures exactly matches Paul’s words. Paul has just quoted from Numbers chapter 16, which contains the account of Korah’s rebellion. So it is possible that Paul refers to that same account and echoes Moses’ words found at Nu 16:26. Those loyal to Jehovah in Moses’ day had to take decisive action and separate themselves from unrighteous ones. Likewise, Paul was encouraging Timothy and other loyal Christians to renounce, or turn away from, all kinds of unrighteousness, including what Paul mentioned in the immediate context​—fights about words, “empty speeches,” apostate teachings, and “foolish and ignorant debates.”​—2Ti 2:14, 16, 18, 23.

calling on the name of Jehovah: This part of the statement may allude to the wording of Isa 26:13 according to the Septuagint. The original Hebrew text of that verse clearly refers to the divine name.​—See App. C3 introduction; 2Ti 2:19b.