2 Timothy 2:19

Here we see what we may comfort ourselves with, in reference to this, and the little errors and heresies that both infect and infest the church, and do mischief. I. It may be a great comfort to us that the unbelief of men cannot make the promise of God of no effect. Though the faith of some particular persons be overthrown, yet the foundation of God standeth sure (Ti2 2:19); it is not possible that they should deceive the elect. Or it may be meant of the truth itself, which they impugn. All the attacks which the powers of darkness have made upon the doctrine of Christ cannot shake it; it stands firm, and weathers all the storms which have been raised against it. The prophets and apostles, that is, the doctrines of the Old and New Testament, are still firm; and they have a seal with two mottoes upon it, one on the one side, and the other on the other, as is usual in a broad seal. 1. One expresses our comfort - that the Lord knows those that are his, and those that are not; knows them, that is, he owns them, so knows them that he will never lose them. Though the faith of some be overthrown, yet the Lord is said to know the ways of the righteous, Psa 1:6. None can overthrow the faith of any whom God hath chosen. 2.

— Matthew Henry's Concise Commentary (public domain)

Nevertheless--Notwithstanding the subversion of their faith, "the firm foundation of God standeth" fast (so the Greek ought to be translated). The "foundation" here is "the Church" [ALFORD], "the ground" or basement support "of the truth" (Ti1 3:15), Christ Himself being the ultimate "foundation" (Co1 3:11). In the steadfast standing of the Church there is involved the steadfast certainty of the doctrine in question (Ti2 2:18). Thus the "house" (Ti2 2:20) answers to the "foundation"; it is made up of the elect whom "the Lord knoweth" (acknowledgeth, recognizes, Psa 1:6; Mat 7:23; Joh 10:14; Co1 8:3) as "His," and who persevere to the end, though others "err concerning the faith" (Mat 24:24; Joh 10:28; Rom 8:38-39; Jo1 2:19). BENGEL takes "the foundation" to be the immovable faithfulness of God (to His promises to His elect [CALVIN]). This contrasts well with the erring from the faith on the part of the reprobate, Ti2 2:18. Though they deny the faith, God abates not His faithfulness (compare Ti2 2:13). having--seeing that it has [ELLICOTT]. seal--"inscription": indicating ownership and destination: inscriptions were often engraven on a "foundation" stone (Rev 21:14) [ALFORD]. This will agree with the view that "the foundation" is the Church (Eph 2:20).

— Jamieson-Fausset-Brown Commentary (public domain)