Exploring the Meaning of Kleis in Greek

κλείς appears in the New Testament with the concrete sense of a “key,” used in scenes where access, restriction, and control over entry are in view. Its six occurrences span teaching about the Kingdom of Heaven and striking apocalyptic images involving Death, Hades, and the abyss.

Occurrences

“I will give to you the keys of the Kingdom of Heaven, and whatever you bind on earth will have been bound in heaven; and whatever you release on earth will have been released in heaven.” (Matthew 16:19)

Here κλείς is plural (“keys”), and it is paired with the language of “bind” and “release.” The “keys of the Kingdom of Heaven” function as an image of authorized control over access: a key is the instrument that opens what is closed and secures what should remain shut. In this saying, the gift of “keys” is immediately explained through the effect of actions “on earth” that correspond to what “will have been” done “in heaven.” The key-imagery therefore frames the following verbs as acts that have real gatekeeping consequences for the realm named, “the Kingdom of Heaven.”

“Woe to you lawyers! For you took away the key of knowledge. You didn’t enter in yourselves, and those who were entering in, you hindered.” (Luke 11:52)

κλείς is singular (“the key”) and attached to “knowledge,” with the outcome described in terms of entry: “You didn’t enter in yourselves, and those who were entering in, you hindered.” The key-image is sharpened by the accusation that it was “took away,” so that the problem is not merely ignorance but the removal of what would enable access. The verse’s own explanation keeps the metaphor anchored: the “key of knowledge” is portrayed as something that opens a way in, and its removal results in hindrance—blocking both the leaders and those already attempting to enter.

“and the Living one. I was dead, and behold, I am alive forever and ever. Amen. I have the keys of Death and of Hades.” (Revelation 1:18)

In this confession, κλείς is again plural (“keys”), now linked to “Death” and “Hades.” The statement “I was dead… I am alive forever and ever” sets a life-and-death horizon for the image: the one speaking holds the means of opening and shutting in relation to Death and Hades. The keys are presented as possessed (“I have”), underscoring mastery and control. In context, the “keys” convey that these feared domains are not autonomous; access and confinement connected with Death and Hades are subject to the key-holder.

“To the angel of the assembly in Philadelphia write: “He who is holy, he who is true, he who has the key of David, he who opens and no one can shut, and who shuts and no one opens, says these things:” (Revelation 3:7)

Here κλείς is singular (“the key”), specified as “of David,” and the verse itself supplies the interpretive frame through parallel clauses: “he who opens and no one can shut, and who shuts and no one opens.” The key is thus portrayed as effectual authority, not merely possession of an object. The emphasis falls on irreversibility from any outside agent: once the key-holder opens, no one can shut; once he shuts, no one can open. In this setting, κλείς symbolizes decisive control over access, with “opens/shuts” explicitly defining what a key does in this scene.

“The fifth angel sounded, and I saw a star from the sky which had fallen to the earth. The key to the pit of the abyss was given to him.” (Revelation 9:1)

In this visionary moment, κλείς is singular (“The key”) and is connected with “the pit of the abyss.” The key is not said to be seized or owned inherently; it “was given to him,” marking delegated authority. The setting is spatial and concrete: a “pit” belonging to “the abyss,” imagined as a locked place that requires a key for access. The giving of the key signals that the fallen star is permitted to act as an opener of that pit; κλείς is the tool and authorization that makes entry into that forbidden depth possible.

“I saw an angel coming down out of heaven, having the key of the abyss and a great chain in his hand.” (Revelation 20:1)

κλείς again appears singular (“the key”), again tied to “the abyss,” but the bearer differs: an angel “coming down out of heaven.” The image combines “the key of the abyss” with “a great chain,” linking the key with securing and restraint. The angel is described as already “having” the key while descending, conveying readiness to exercise control over the abyss. In this scene, κλείς belongs to the same locked realm as in Revelation 9:1, but the accompanying chain highlights the key’s role in a broader act of confinement and control over what the abyss contains.

Sense and Usage

Across these passages κλείς retains the straightforward idea of a key, but the texts use that everyday object to speak about real authority over access. Sometimes the emphasis lies on being granted keys (Matthew 16:19) or being given a key (Revelation 9:1); sometimes it lies on having keys as a settled possession (Revelation 1:18; Revelation 20:1). The difference in phrasing matters within the imagery: “I will give to you the keys…” (Matthew 16:19) and “was given to him” (Revelation 9:1) present keys as conferred authority, whereas “I have the keys…” (Revelation 1:18) and “having the key…” (Revelation 20:1) present keys as held power already in hand.

The word also alternates between plural and singular. In Matthew 16:19 and Revelation 1:18, “keys” are plural, attached to large domains (“the Kingdom of Heaven,” “Death and… Hades”). In Luke 11:52, Revelation 3:7, Revelation 9:1, and Revelation 20:1 the noun is singular, attached to a specified sphere (“knowledge,” “David,” “the pit of the abyss,” “the abyss”). The singular can feel pointed and concentrated: one key that decisively governs a particular lock. The plural can convey breadth across a paired or expansive domain, as when both “Death” and “Hades” are named together under the authority of the key-holder.

Several occurrences explicitly describe what the key accomplishes. Revelation 3:7 states the functional outcome in balanced clauses—opening that no one can shut, and shutting that no one can open—making κλείς a vivid shorthand for effective control. Luke 11:52 likewise defines the key’s effect by describing the results of its removal: the leaders fail to “enter in” and they “hinder” others who were entering. Even without repeating the verbs “open” and “shut,” the scene assumes that a key has a direct relationship to entry. Matthew 16:19 ties key-imagery to binding and releasing actions whose consequences reach from earth to heaven, using the key as a picture of authoritative decisions connected to the Kingdom of Heaven.

In Revelation, κλείς is repeatedly attached to places or powers that are imagined as closed off: “Death and… Hades” (Revelation 1:18) and “the pit of the abyss… the abyss” (Revelation 9:1; Revelation 20:1). The key belongs to, and controls, what is otherwise inaccessible. That is why the scenes stress who holds it—one who is “alive forever and ever” (Revelation 1:18), one described as “holy” and “true” (Revelation 3:7), a fallen “star” who receives it (Revelation 9:1), and an angel descending from heaven with it (Revelation 20:1). In each case, the key marks the bearer as the one empowered to open or secure the realm named.

Imagery

The passages use κλείς to make authority visible. A key is small, graspable, and practical; in these texts it becomes a concentrated symbol for decisions that admit, exclude, release, or confine. Whether the setting is the “Kingdom of Heaven” (Matthew 16:19), the realm of “knowledge” that leads to “enter[ing] in” (Luke 11:52), or the ominous spaces of “Death… Hades… the pit of the abyss… the abyss” (Revelation 1:18; Revelation 9:1; Revelation 20:1), the repeated image is the same: whoever holds the key governs the doorway.

Sources: Lexical data from Strong’s Exhaustive Concordance and the Translators Brief Lexicon of Extended Strongs for Greek (STEPBible, CC BY). Occurrence data from the Translators Amalgamated Greek New Testament (STEPBible, CC BY). Scripture quotations from the World English Bible (public domain).