Light from Light: A Non-Heretical Analogy for the Trinity



It seems to be an unwritten rule that whenever an analogy for the Trinity is given, one must begin with the disclaimer that “all analogies break down.” The reason, though, that all analogies break down is simply because analogies compare things that are not exactly alike (if they were, it would not be an analogy!). However, analogies are not truly “broken” unless they are “false analogies“- that is, they purport to compare two things in a way that they do not actually compare. In the case of the Trinity, most analogies are truly broken because the very thing they claim to explain often requires a heretical understanding of the Godhead.

There are two affirmations that must be understood to grasp the true theological definition of the Trinity:

  1. There is only one God. (Dt. 6:4; Isa. 44:6; 1 Cor. 8:6; Eph. 4:6; 1 Tim. 2:5).
  2. There are three distinct persons (Ps. 45:6, 110:1; Isa 63:7-10; Zech 1:12; Mt. 3:16-17, 28:19; Lk. 23:46; 2 Cor. 13:14) who are each fully God:
    • The Father (Jn. 6:27; Rom. 1:7; Gal. 1:1)
    • The Son (Mk. 2:5; 14:61-65; Jn. 1:1-5; 8:58; 10:11; Col 1:15-17; Heb. 1:1-15; Rev. 1:17)
    • The Holy Spirit (Gen 1:2 (cf. Isa. 44:6; Isa 63:7-9; Ps. 139:7; Acts 5:3-4; 2 Cor. 13:14; Heb 9:14)

While there are numerous ways to misunderstand these two points, the most common are either a denial of 1 (e.g., Tri-Theism, which mistakenly affirms the existence of three gods) or a denial of 2 (e.g., Modalism, which mistakenly affirms only the existence of three roles that the one God performs). I deal with these heresies elsewhere. Here I just wanted to discuss one analogy that, while it is not “perfect” (what analogy is?), is not heretical.

Light from Light from Light

A Good Theological Analogy

A stream of light is a surprisingly good analogy for the Trinity. It is one “thing,” yet can be distinguished into three components.

It’s “threeness” consists of the light’s source, beam, and spot. The source is, in a sense, hidden (we are not talking about the bulb here, but the emanating light from which comes the beam or spot that we do see). The spot (a visible manifestation of the light when it hits the reflecting surface), and the beam (usually invisible unless enlightening material particles in its path) connects the spot and source. This correlates well with the relations of the persons in the Trinity: the invisible Father sends the Son (who is invisible until contacting matter) and the invisible Spirit to manifest in various ways on Earth.

As to its unity – a light stream consists of single source and is made up of a single substance. While the three components are distinguishable, they are not really distinct parts. Further, even though there is a causal relation between the components, a stream of light exists all-at-once requiring all components simultaneously. Finally, while this unity has a sort of built-in “subordination,” it is not one of essence nor importance.

A Good Biblical Analogy

This analogy is also supported by the Bible. God is often spoken of in terms of light in the Old Testament, for example:

  • 2 Samuel 22:29 – You are my lamp, O LORD; the LORD turns my darkness into light.
  • Psalm 4:6 – Let the light of your face shine upon us, O LORD.
  • Psalm 36:9 – For with you is the fountain of life; in your light we see light.
  • Psalm 43:3 – Send forth your light and your truth, let them guide me;
  • Psalm 89:15 – Blessed are those who have learned to acclaim you, who walk in the light of your presence, O LORD.
  • Isaiah 60:19 – The sun will no more be your light by day, nor will the brightness of the moon shine on you, for the LORD will be your everlasting light, and your God will be your glory.
  • Daniel 2:22 – He reveals deep and hidden things; he knows what is in the darkness, and the light dwells with him.

Several authors of the New Testament (especially the Apostle John) speaks of God as light. In fact, if we count a few indirect references to Christ and light in the synoptic gospels, every New Testament writer references light with regard to God:

  • Matthew 4:16 / Luke 1:79 – the people dwelling in darkness have seen a great light, and for those dwelling in the region and shadow of death, on them a light has dawned.
  • Mark 9:2-3 – And he was transfigured before them,  and his clothes became radiant, intensely white, as no one on earth could bleach them.
  • John 1:4-5 – In him was life, and that life was the light of men. The light shines in the darkness, but the darkness has not understood it.
  • John 3:19-20 – Light has come into the world, but men loved darkness instead of light because their deeds were evil. Everyone who does evil hates the light, and will not come into the light for fear that his deeds will be exposed.
  • John 8:12 / 9:5 – I am the light of the world.
  • 2 Corinthians 4:6 – For God, who said, “Let light shine out of darkness,” has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.
  • Ephesians 5:14 – For anything that becomes visible is light. Therefore it says, “Awake, O sleeper, and arise from the dead, and Christ will shine on you.”
  • 1 Timothy 6:16 – Who alone has immortality, who dwells in unapproachable light, whom no one has ever seen or can see.
  • Hebrews 1:3 – He is the radiance of the glory of God and the exact imprint of his nature.
  • James 1:17 – Every good gift and every perfect gift is from above, coming down from the Father of lights with whom there is no variation or shadow due to change.
  • 1 Peter 2:9 – But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light.
  • 1 John 1:5 – God is light, and in him is no darkness at all.
  • Revelation 21:23 – And the city has no need of sun or moon to shine on it, for the glory of God gives it light, and its lamp is the Lamb.

Even when these metaphorical, I believe the metaphor of light was chosen for a reason.

A Good Traditional Analogy

The phrase “light from light” is actually taken from the affirmation in the Nicene Creed where Jesus is said to be “God from God, Light from Light, true God from true God.” This was in direct response to the heresy of Arius, who taught that the Son was a lesser, created being.

Tertullian, for example, said of the Son of God that, “we have been taught that he proceeds forth from God, and in that procession He is generated; so that He is the Son of God, and is called God from unity of substance with God. . . . Thus Christ is Spirit of Spirit, and God of God, as light of light is kindled” (Apology, 21).

In another polemical text, Justin Martyr argues that, “they call Him the Word, because He carries tidings from the Father to men: but maintain that this power is indivisible and inseparable from the Father, just as they say that the light of the sun on earth is indivisible and inseparable from the sun in the heavens; as when it sinks, the light sinks along with it” (Dialogue With Trypho, CXXVIII)

Moreover, Athanasius , the great defender of the faith, used light as an analogy to refute the errors of Arius in his De Decretis:

  • He was always, existing everlastingly with the Father, as the radiance of light)
  • . . . the Word is ever in the Father and the Father in the Word, as the radiance stands towards the light (for this the phrase itself indicates), therefore the Council, as understanding this, suitably wrote ‘one in essence,’ that they might both defeat the perverseness of the heretics, and show that the Word was other than originated things.
  • . . . he who does not hold with Arius, must needs hold and intend the decisions of the Council, suitably regarding them to signify the relation of the radiance to the light, and from thence gaining the illustration of the truth.
  • . . . the illustration of the Light and the Radiance has this meaning. For the Saints have not said that the Word was related to God as fire kindled from the heat of the sun, which is commonly put out again, for this is an external work and a creature of its author, but they all preach of Him as Radiance, thereby to signify His being from the essence, proper and indivisible, and His oneness with the Father. This also will secure His true unchangableness and immutability . . .
  • . . . let every corporeal reference be banished on this subject; and transcending every imagination of sense, let us, with pure understanding and with mind alone, apprehend the genuine relation of son to father, and the Word’s proper relation towards God, and the unvarying likeness of the radiance towards the light
  • for as the words ‘Offspring’ and ‘Son’ bear, and are meant to bear, no human sense, but one suitable to God, in like manner when we hear the phrase ‘one in essence,’ let us not fall upon human senses, and imagine partitions and divisions of the Godhead, but as having our thoughts directed to things immaterial, let us preserve undivided the oneness of nature and the identity of light
  • God is truly Father of the Word. Here again, the illustration of light and its radiance is in point. Who will presume to say that the radiance is unlike and foreign to the sun? Rather who, thus considering the radiance relatively to the sun, and the identity of the light, would not say with confidence, ‘Truly the light and the radiance are one, and the one is manifested in the other, and the radiance is in the sun, so that whoso sees this, sees that also?’ . . . evidently He it is who is from the Father: for all things originated partake of Him, as partaking of the Holy Ghost. And being such, He cannot be from nothing, nor a creature at all, but rather a proper Offspring from the Father, as the radiance from light.


The reason this is a good analogy is that, at least in the parts it claims to illustrate, it does not state or imply a false heretical view. Light as an analogy for the Trinity will, like all analogies, “break down” at some point. Ultimately, the exact nature of the Trinity is not expressible in terms taken from our knowledge of the created order because nothing in the created order is a true Trinity. This analogy’s problems, however, arise mostly from scientific inaccuracy: we must assume the basic perceptive view of light as a single unit (rather than a wave or particle) with an instantaneous procession from its source. But this is no worse than comparing God to a rock (e.g., Ps. 18:2). Prescinding from inaccuracies of perception, though, it is an illustration that is both theologically, biblically, and traditionally useful.

For who can even imagine that the radiance of light ever was not, so that he should dare to say that the Son was not always, or that the Son was not before His generation? Or who is capable of separating the radiance from the sun, or to conceive of the fountain as ever void of life, that he should madly say, ‘The Son is from nothing,’ who says, ‘I am the life John 14:6,’ or ‘alien to the Father’s essence,’ who, says, ‘He that has seen Me, has seen the Father ?’ for the sacred writers wishing us thus to understand, have given these illustrations; and it is unseemly and most irreligious, when Scripture contains such images, to form ideas concerning our Lord from others which are neither in Scripture, nor have any religious bearing.
(St. Athanasius, De Decretis – emphasis added)