A.T. Robertson Commentary Revelation 3:8

"I know thy works (behold, I have set before thee a door opened, which none can shut), that thou hast a little power, and didst keep my word, and didst not deny my name." — Revelation 3:8 (ASV)

I have set (δεδωκα). Perfect active indicative of διδωμ, "I have given" (a gift of Christ, this open door). See Lu 12:51 for a like use of διδωμ.

A door opened (θυραν ηνεωιγμενην). Perfect (triple reduplication) passive predicate participle of ανοιγω (verse 7) accusative feminine singular. The metaphor of the open door was a common one (John 10:7–9; Acts 14:27; 1 Corinthians 16:9; 2 Corinthians 2:12; Colossians 4:3; Revelation 3:20; Revelation 4:1). Probably it means here a good opportunity for missionary effort in spite of the Jewish hostility.

Which (ην--αυτην). Pleonastic vernacular and Hebrew repetition of the personal pronoun αυτην (it) after the relative ην (which). Direct reference to the statement in verse 7.

That (οτ). This conjunction resumes the construction of οιδα σου τα εργα (I know thy works) after the parenthesis (ιδου--αυτην, Behold--shut).

A little power (μικραν δυναμιν). Probably "little power," little influence or weight in Philadelphia, the members probably from the lower classes (1 Corinthians 1:26f.).

And didst keep (κα ετηρησας). "And yet (adversative use of κα) didst keep" (first aorist active indicative of τηρεω) my word in some crisis of trial. See Joh 17:6 for the phrase "keeping the word."

Didst not deny (ουκ ηρνησω). First aorist middle indicative second person singular of αρνεομα. The issue was probably forced by the Jews (cf. 2:9), but they stood true.