You have met three of the Greek verb's principal parts: the present, the future and the aorist. This chapter introduces the fourth, the perfect, and with it the pluperfect that is built on the same stem.
The perfect is the tense most often preached on and the one most often overstated. What it actually claims is narrow, and worth holding precisely.
Completed action, continuing state
The perfect presents an action as complete, and presents the state resulting from it as still standing. The weight usually falls on the present state rather than on the past act.
Paul puts the contrast inside one sentence:
καὶ ὅτι ἐτάφη, καὶ ὅτι ἐγήγερται τῇ ἡμέρᾳ τῇ τρίτῃ κατὰ τὰς γραφάς
"And that he was buried, and that he has been raised on the third day according to the Scriptures." ἐτάφη is an aorist — the burial presented as one whole event, and nothing said about what followed it. ἐγήγερται is a perfect. Paul is not only saying that the resurrection happened; he is saying that it happened and that Christ is risen still. Swap in an aorist and the sentence still reports the event and stops saying the second thing.
That is what the form is for. It is not a promise about what every instance of it achieves, which is where this chapter ends.
The form: reduplication and κα
Three things happen, and none of them is an augment.
1. The first consonant of the stem is doubled with an ε between: λυ- becomes λελυ-. This is reduplication, and it is the perfect's signature.
2. κα is added after the stem.
3. The endings are the perfect's own: -α, -ας, -ε(ν), -αμεν, -ατε, -ασι(ν). They are close to the secondary active set from chapter 7 in the middle, and differ at both ends.
So λύω gives λέλυκα, λέλυκας, λέλυκε(ν), λελύκαμεν, λελύκατε, λελύκασι(ν) — the full column is in Tables, beside the four tenses you already have. Note that the first singular has no ν and the third ends in -ε(ν), which is what keeps them apart.
Real examples look exactly like that. First person: πιστεύω → πεπίστευκα, λαλέω → λελάληκα. Third: ποιέω → πεποίηκεν, μαρτυρέω → μεμαρτύρηκεν.
When the reduplication is not a plain doubling
Three kinds of stem will not take a doubled consonant. You do not need the rules to recite, only the shapes to recognise.
A stem beginning with a vowel lengthens it instead, which makes it look exactly like an augment:
Ἤγγικεν ἡ βασιλεία τῶν οὐρανῶν
"The kingdom of heaven has drawn near." ἐγγίζω becomes ἤγγικεν, and the perfect is the point: it has come near, and it is near.
A stem beginning with two consonants usually gives up and uses a bare ἐ-. γινώσκω becomes ἔγνωκεν — the root behind it is γνο-, and you cannot double a γν. The exception is a second consonant λ or ρ, which reduplicates as normal: γράφω becomes γέγραφα.
A stem beginning with an aspirate — φ, θ, χ — reduplicates with the unaspirated partner π, τ, κ, because Greek will not have two rough sounds in successive syllables:
δικαιοσύνη θεοῦ πεφανέρωται
"A righteousness of God has been revealed." φανερόω gives πε-, not φε-.
The habit is simpler than the rules: a doubled first syllable, or a lengthened first vowel with a κ further in, means perfect.
Second perfects
Some verbs form the perfect without the κ. They are conjugated identically otherwise, and — as with first and second aorists in chapter 7 — the difference is one of form only. A second perfect means everything a first perfect means.
γίνομαι → γέγονεν · γράφω → γέγραφα · ἔρχομαι → ἐλήλυθεν · λαμβάνω → εἴληφεν · πείθω → πέποιθεν · ἀκούω → ἀκηκόαμεν
Ὃ γέγραφα γέγραφα
"What I have written, I have written." Pilate says it twice, in the perfect both times, and the tense is why the sentence closes the matter. Not "I wrote it" but "it is written, and it stands".
The perfect in the text
γέγραπται is the standard formula for introducing Scripture — 67 occurrences — and it is a perfect. Not "it was written once", but "it stands written".
εἶπεν· Τετέλεσται
"He said, 'It is finished.'" One word: finished then, finished still. (Both of these are passives, which come later; the tense is what is in view.)
τὸν καλὸν ἀγῶνα ἠγώνισμαι, τὸν δρόμον τετέλεκα, τὴν πίστιν τετήρηκα
"I have fought the good fight, I have finished the race, I have kept the faith." Three perfects in a row — not three past events, but where Paul now stands as a result of them.
The pluperfect
The pluperfect is the past of the perfect: complete, with results that stood at some past moment. It takes an augment as well as the reduplication and inserts -ει- before the endings — ἐλελύκειν, ἐλελύκεις, ἐλελύκει.
ἐγίνωσκεν γὰρ ὅτι διὰ φθόνον παραδεδώκεισαν αὐτὸν οἱ ἀρχιερεῖς
"For he knew that the chief priests had handed him over out of envy." παραδεδώκεισαν does exactly what it says: they had done it, and it stood done while Pilate weighed what to do next.
It is rare — 88 pluperfects in the whole New Testament against 1,572 perfects — so recognition is the goal and drilling it is not worth your week. And of those 88, thirty-four belong to οἶδα and fourteen to ἵστημι, and neither of those is translated as a past perfect at all. Which brings us to the largest fact in the chapter.
οἶδα, and ᾔδειν
οἶδα means "I know". It is perfect in form and present in meaning, and it occurs 296 times.
Here it is. 210 of those are perfect active indicatives — one in three of every perfect active indicative in the New Testament — and not one means "I have known". Parse οἶδα as the perfect it is and then read it as a present, "I know" — which is the discipline chapter 2 set out, and the reason it matters. Its pluperfect ᾔδειν is the same trick one tense further back: pluperfect in form, "I knew" in meaning.
ἵστημι behaves the same way: ἕστηκα is "I have taken my stand", which in English is simply "I am standing".
μέσος ὑμῶν ἕστηκεν ὃν ὑμεῖς οὐκ οἴδατε
"Among you stands one whom you do not know." Two perfects, and almost no English Bible renders either as one — because in both the resulting state is the point and the past act has receded from view. Young’s Literal is the exception again, "he hath stood ... ye have not known", which shows you what the others are declining to say. Which is the perfect working exactly as described.
Don't over-preach it
This is the tense most likely to be pushed too far from a pulpit, and it is worth naming what pushing it looks like.
The form does not guarantee emphasis. Some verbs simply live in the perfect — οἶδα, ἕστηκα, γέγονεν, πέποιθα. There it is a fact about the vocabulary, not a decision by the author.
The choice belongs to the writer's viewpoint, not to the events. A perfect says the writer wanted the result in view; it does not say the event was different.
So ask two questions before building on it. Could an aorist have stood here, and does the sentence around it care about the result? Where the answer to both is yes — Paul on the resurrection, John at the cross — the perfect is carrying real weight, and it is worth saying so.
That is not scepticism. The perfect really is the most exegetically loaded tense in Greek. It is simply not loaded every time.