καιρός kairos — appointed time, opportune moment, decisive instant

The word

καιρός (kairos) is the Greek noun for the right time, the opportune moment, the appointed time, the decisive instant. It appears approximately 86 times in the New Testament and is distinct in classical Greek usage from χρόνος (chronos) — clock time, durational time, the period that elapses.

The distinction is structural in classical Greek and is preserved in New Testament Greek:

• Chronos — the running of the clock, the duration of a period, the elapse of time.
• Kairos — the moment when something becomes possible. The cusp. The window. The “now is the time” of a specific occasion.

Both English-language translations of “time” can serve for either, which means the distinction Greek makes is largely invisible to English readers.

The classical distinction

The pre-Socratic philosophers used kairos for the propitious moment — the moment when an archer must release the arrow, the moment when a sailor must catch the wind, the moment when an opportunity opens. Pindar’s odes celebrate athletes who seized the kairos. Greek rhetoric had a technical doctrine of kairos — the orator’s responsibility to say the right thing at the right time, adjusting argument to the moment.

The early Christian writers inherit this vocabulary intact. When the New Testament says kairos, it is not using a religious neologism; it is using the standard Greek word for “the moment when something matters.”

Mark 1:15 — the proclamation

The most theologically loaded New Testament use is Mark 1:15 — Jesus’s opening preaching:

πεπλήρωται ὁ καιρὸς καὶ ἤγγικεν ἡ βασιλεία τοῦ θεοῦ.

The time (kairos) is fulfilled, and the kingdom of God has come near.

The Greek says peplērōtai ho kairos — “the kairos has been fulfilled,” perfect passive. The verb plēroō (πληρόω, “to fill, to fulfill”) signals that an appointed measure has been reached. The kairos was appointed — by God, in the prophetic tradition — and it has now come full. This is not duration; this is the arrival of the appointed moment.

English “the time is fulfilled” gestures toward this but reads more passively in English than in Greek. The Greek says something closer to “the appointed-moment-spoken-of-by-the-prophets has arrived.” Loss in translation: not the basic meaning, but the precision.

Galatians 4:4 — the fullness of time

A parallel theological passage: Galatians 4:4:

ὅτε δὲ ἦλθεν τὸ πλήρωμα τοῦ χρόνου, ἐξαπέστειλεν ὁ θεὸς τὸν υἱὸν αὐτοῦ

But when the fullness of time (chronos) had come, God sent His Son.

Here Paul uses chronos — but with plēroma (fullness). The grammatical move is similar: Paul is talking about the completion of a period. Chronos-fullness, not kairos-arrival. The distinction is finely calibrated: Mark 1:15 stresses the moment-of-decision; Galatians 4:4 stresses the completion-of-the-era.

A reader who collapses both into English “time” loses the distinction. The two passages are saying related but not identical things.

Romans 13:11 — the alarm

Romans 13:11:

καὶ τοῦτο εἰδότες τὸν καιρόν, ὅτι ὥρα ἤδη ὑμᾶς ἐξ ὕπνου ἐγερθῆναι

And do this, understanding the time (kairos): the hour (hōra) has already come for you to wake from sleep.

The Greek uses kairos and hōra together — the appointed moment of the gospel age, and the hour within it. The line reads in English as ordinary urgency; in Greek, it has the apocalyptic precision of a watchman calling out at a particular hour because the kairos requires it.

Ephesians 5:16 — “redeeming the time”

Ephesians 5:16:

ἐξαγοραζόμενοι τὸν καιρόν, ὅτι αἱ ἡμέραι πονηραί εἰσιν

The KJV reads “redeeming the time, because the days are evil.” The BSB reads “redeeming the time, because the days are evil.” The Greek exagorazomenoi ton kairon — literally “buying out the kairos” — uses the metaphor of buying back something valuable, with kairos as the object being purchased. The KJV/BSB rendering preserves the metaphor at the cost of obscuring the “opportunity” sense; modern copyrighted translations (NIV, NLT, ESV, NASB) tend to opt for opportunity-emphasising phrasings, which recover the kairos-as-opportunity sense at the cost of the buying metaphor. Both directions of translation are working with the same Greek word doing both jobs.

2 Corinthians 6:2 — now is the favourable kairos

2 Corinthians 6:2 quotes Isaiah 49:8 and adds:

ἰδοὺ νῦν καιρὸς εὐπρόσδεκτος, ἰδοὺ νῦν ἡμέρα σωτηρίας

Look, now is the acceptable time (kairos), now is the day of salvation.

The Greek kairos euprosdektos — “acceptable, favourable kairos” — is the moment when God’s offer is open. The verse is the source of much later Christian preaching on the “today” of salvation. The point is precisely kairos: not duration, but window-of-opportunity that is open now.

Where kairos and chronos appear together

The cleanest example of the two words used in contrast is Acts 1:7, where Jesus tells the disciples before the ascension:

οὐχ ὑμῶν ἐστιν γνῶναι χρόνους ἢ καιρούς

It is not for you to know the times (chronoi) or the appointed seasons (kairoi).

Greek uses both, plural. The KJV preserves the doublet: “It is not for you to know the times or the seasons.” The BSB renders the same as “the times or seasons.” Modern copyrighted translations either keep the doublet pattern or collapse to a single English noun (“dates,” “schedule”) — losing the two-word distinction the Greek deliberately deploys. The two Greek words are being used in deliberate contrast — the durations and the appointed moments alike — and the contrast is the point.

A similar pair appears in 1 Thessalonians 5:1 (“about times and seasons” — peri tōn chronōn kai tōn kairōn).

The Hebrew background

The Hebrew Bible’s vocabulary for time has a parallel distinction. ʿEt (עֵת, “time, season”) is the common word — used famously throughout Ecclesiastes 3 (“a time to be born, and a time to die”). The Hebrew moʿed (מוֹעֵד) specifically names appointed time — used for festivals (the moʿadim) and for prophetic appointed moments. The Septuagint translates Hebrew moʿed most often as kairos; the Hebrew ʿet is translated by kairos or chronos depending on context.

So the New Testament’s kairos-vocabulary is not a Greek innovation in religious time-talk — it tracks a Hebrew distinction (ʿet / moʿed) that ran through the Septuagint into the Greek New Testament.

What gets flattened

When an English Bible renders kairos and chronos both as “time,” the reader receives a single English word doing the work of two Greek words. The distinction — between the running clock and the appointed moment — disappears.

This matters in passages where the urgency of the kairos is the point. Mark 1:15’s “the kairos is fulfilled” is not a chronological statement; it is an announcement that the appointed moment has arrived. Romans 13:11’s “the kairos” is not duration but cusp. Some translations note the underlying Greek in margins; most do not.

The English reader can recover the distinction only by knowing the Greek lexical fact: there are two words; when the New Testament wants to say “right moment, decisive moment, appointed cusp,” it says kairos.

Related reading

• Logos — word, reason, account — another Greek word whose semantic range is flattened in English translation
• The meaning of “in the fullness of time” — the Galatians 4:4 phrase, where Paul uses chronos rather than kairos