Passage
But the sure foundation of God standeth firm, having this seal: the Lord knoweth who are his; and let every one depart from iniquity who nameth the name of the Lord.
2 Timothy 2:19 (DRB)
Nearby Context
2 Timothy 2:17 And their speech spreadeth like a canker: of whom are Hymeneus and Philetus:
2 Timothy 2:18 Who have erred from the truth, saying that the resurrection is past already, and have subverted the faith of some.
2 Timothy 2:19 But the sure foundation of God standeth firm, having this seal: the Lord knoweth who are his; and let every one depart from iniquity who nameth the name of the Lord.
2 Timothy 2:20 But in a great house there are not only vessels of gold and of silver, but also of wood and of earth: and some indeed unto honour, but some unto dishonour.
2 Timothy 2:21 If any man therefore shall cleanse himself from these, he shall be a vessel unto honour, sanctified and profitable to the Lord, prepared unto every good work.
Study Lenses
The verse centers on "sure", "foundation", "standeth", "firm", "having", "seal", "lord", and "knoweth". It is saying that the verse draws attention to "sure" and "foundation", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 18's "Who have erred from the truth saying..." into verse 20's "But in a great house there are...", so "sure" and "foundation" belong inside that flow. In 2 Timothy context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "sure" and "foundation" with trust shaped by these words, not by a vague optimism outside the passage.