The biblical writers proclaim that only one God exists, yet
they also refer to three persons as “God.” The Father,
the Son, and the Holy Spirit are all God. Furthermore, these three
persons relate to one another as self-conscious individuals. Jesus
prays to the Father (John 17). The Father speaks from heaven
concerning the Son (Matt. 3:17; Luke 3:22). Jesus vows to send the
Spirit as “Advocate” after his ascension, and he will do
what Jesus himself did while he was among us (John 16:7–8). The
challenge of Christian theology, therefore, is to formulate a
doctrine of God that captures all these elements, each of which
surfaces in both Testaments.
Old
Testament
In
the OT, evidence for the Trinity appears mostly at the implicit
level. Yahweh is called “Father” in Isaiah (63:16; 64:8),
Jeremiah (3:4, 19; 31:9), and Malachi (2:10). Isaiah declares, “But
you are our Father, though Abraham does not know us or Israel
acknowledge us; you, Lord, are our Father, our Redeemer from of old
is your name” (Isa. 63:16). Yahweh identifies himself as
“Father” implicitly when he claims Israel as his “son”
(Hos. 11:1), and the same principle applies to Ps. 2:7, where God
declares to his anointed, “You are my son; today I have become
your father.” These cases do not compare in numbers with the NT
evidence, but a person thought of as “God the Father”
certainly appears in the OT.
Messianic
texts of the OT introduce us to God the Son. In Isa. 9:6 a “child
is born” who will be called “Wonderful Counselor, Mighty
God, Everlasting Father, Prince of Peace.” The day of
“Immanuel,” or “God with us,” is foreshadowed
in Isa. 7:14 (cf. Matt. 1:22), while Isa. 40:3–5 anticipates
the appearance of the Lord “in the wilderness” (cf. Matt.
3:3). Daniel sees “one like a son of man, coming with the
clouds of heaven” being given “authority, glory and
sovereign power” (Dan. 7:13–14). In Ps. 110:1 Yahweh says
to David’s “Lord,” “Sit at my right hand
until I make your enemies a footstool for your feet.”
Similarly,
the OT seems to distinguish the Spirit of God from Yahweh while
implying the Spirit’s own personality. Genesis 1:2 makes that
case, as does Exod. 31:3, where Yahweh fills Bezalel with the “Spirit
of God” (cf. Exod. 35:31; Num. 11:29). In 1 Sam. 16:14 a
contrast is made between the “Spirit of the Lord” that
leaves Saul and an “evil spirit from the Lord” that
torments him; also we find a repentant David pleading that God would
not take away his “Holy Spirit” (Ps. 51:11). The Spirit
can be put on persons by God, with the result that they prophesy
(Isa. 61:1; Joel 2:28–29) and do what pleases him (Ezek.
36:26–27). In the OT, therefore, we see two persons (the Son
and the Holy Spirit) who are both God and also distinguishable from
one to whom they answer and by whom they are sent.
New
Testament
The
NT contains abundant evidence for “God the Father,” often
because of Jesus’ teaching. The “Father” appears
several times in the Sermon on the Mount (e.g., Matt. 5:16; 6:6–9,
14, 18, 26, 32; 7:11). Matthew 7:21 stands out because of Jesus’
reference to “my Father who is in heaven,” by which he
identifies himself as the Son (see also Matt. 15:13; 16:17; 18:10;
and Luke 24:49). Paul’s greetings normally come from God the
Father and the Lord Jesus Christ, as seen in Rom. 1:7: “Grace
and peace to you from God our Father and from the Lord Jesus Christ”
(also 1 Cor. 1:3; 2 Cor. 1:2; Gal. 1:1–3; 1 Tim.
1:2; 2 Tim. 1:2). Paul introduces the Father and the Son in
1 Cor. 8:6: “For us there is but one God, the Father, from
whom all things came and for whom we live; and there is but one Lord,
Jesus Christ, through whom all things came and through whom we live”
(see also 1 Cor. 15:24; 2 Cor. 11:31; Eph. 1:3; Phil.
2:22). Other significant texts include Heb. 1:5; 1 Pet. 1:2–3;
in the latter, the scattered believers are those “who have been
chosen according to the foreknowledge of God the Father, through the
sanctifying work of the Spirit, to be obedient to Jesus Christ and
sprinkled with his blood. . . . Praise be to the God
and Father of our Lord Jesus Christ!” The NT evidence for “God
the Father” is clear.
Biblical
texts that point to the deity of Christ supply evidence for the
second claim: the Son is God. Some of the texts listed above say as
much, but one can take this case further. In context, John’s
prologue refers to Jesus as the “Word” and proclaims that
he was “with God” and “was God” (John 1:1).
Jesus also relates to the Father in ways that imply his own deity, as
he declares in John 10:30, “I and the Father are one.”
After significant doubting, Thomas confesses the deity of Christ in
John 20:28: “My Lord and my God!” NT passages that
identify Jesus as the “Son of God” point to his deity, as
Peter does in Matt. 16:16: “You are the Messiah, the Son of the
living God.” Even demons identify Jesus as the Son. They call
out, “What do you want with us, Son of God? . . .
Have you come here to torture us before the appointed time?”
(Matt. 8:29; cf. Mark 5:7). The so-called Christ Hymn of Phil. 2:6–11
puts Jesus on the level with God, saying that he did not consider
“equality with God something to be used to his own advantage.”
The author of Hebrews declares that Jesus is “the radiance of
God’s glory and the exact representation of his being”
(1:3). Colossians 1:15–16 says that Jesus is the “image
of the invisible God, the firstborn over all creation” and the
one by whom “all things were created,” and Col. 1:19
states that “God was pleased to have all his fullness dwell in
him.” According to Titus 2:13, Jesus is “our great God
and Savior.” The entire sequence of Rev. 4–5 highlights
the deity of Christ, culminating in the praise “To him who sits
on the throne and to the Lamb be praise and honor and glory and
power, for ever and ever!” as both the Enthroned One and the
Lamb are worshiped as God (5:13–14).
The
NT writers underscore both the deity and the distinctive personality
of the Holy Spirit. Jesus is conceived in Mary’s womb by the
Spirit’s power (Matt. 1:18–20), and when Jesus is
baptized, the Spirit descends upon him as a dove (Matt. 3:16; Mark
1:10). Jesus drives out demons by the Spirit, and one dare not speak
against the Spirit when he does so (Matt. 12:28–32). Luke’s
Gospel puts added emphasis on the ministry of the Spirit, as we also
see in Acts. He empowers various people to praise and prophesy (Luke
1:41, 67) and to be witnesses for Christ (Acts 1:8; 2:4, 17–18,
38). Sinners can lie to the Holy Spirit (Acts 5:3, 9), and the Holy
Spirit bears witness along with the apostles to the risen Christ
(5:32). In John’s Gospel, the Spirit becomes the counselor and
teacher of the disciples, reminding them of their Lord’s
instructions (John 14:26; 16:13). The Spirit brings assurance of
sonship (Rom. 8:16) and helps disciples when they pray (8:26). This
person even knows the very thoughts of God (1 Cor. 2:11).
Accordingly, the Great Commission requires baptism in the name of the
Father, the Son, and the Holy Spirit (Matt. 28:19). All three members
of the Trinity have a part in the advancement of the kingdom, the
Spirit no less than the Father and the Son.
Relationships
between Father, Son, and Spirit
The
evidence considered thus far demonstrates that three persons are
called “God” in Scripture: the Father, the Son, and the
Holy Spirit. But the Scriptures also point to a chain of command in
their relationship to one another. The Son obeys the Father, and the
Spirit proceeds from the Father and the Son to apply the work of the
cross to the church. This “functional subordination” of
the Son to the Father, some might argue, would follow simply from the
analogy chosen by God to reveal himself to us. The “Son”
would obey his “Father,” not vice versa, though they
share a common dignity as God, just as a human father and son share a
common humanity. But the NT writers expressly tell us that they
relate to each other in this way. In Matt. 11:27 (cf. Luke 10:22)
Jesus announces, “All things have been committed to me by my
Father” (cf. John 3:35; 5:22). The latter transfers authority
to the former as his subordinate. The Father even (for a season)
knows more than the Son regarding the last days: “About that
day or hour no one knows, not even the angels in heaven, nor the Son,
but only the Father” (Matt. 24:36), though he also dignifies
the Son: “For the Father loves the Son and shows him all he
does” (John 5:20). The Son’s commitment to please his
heavenly Father is a prominent theme of the NT, as Jesus declares in
John 5:19: “The Son can do nothing by himself; he can do only
what he sees his Father doing, because whatever the Father does the
Son also does.” No text brings out this dependence of the Son
upon the Father more clearly than Heb. 5:7–8, where the Son is
said to have “offered up prayers and petitions with fervent
cries and tears to the one who could save him from death, and he was
heard because of his reverent submission. Son though he was, he
learned obedience from what he suffered.” It is debated by
theologians whether this functional subordination relates only to the
period of the Son’s earthly ministry, or whether it is an
eternal subordination.
The
Spirit, though equal in personality and dignity with the Father and
the Son, proceeds from them to apply the work of the cross and
empower the church for ministry. In John 14:26 Jesus says, “The
Advocate, the Holy Spirit, whom the Father will send in my name, will
teach you all things and will remind you of everything I have said to
you.” In John 15:26 Jesus announces that he also sends the
Spirit out: “When the Advocate comes, whom I will send to you
from the Father—the Spirit of truth who goes out from the
Father—he will testify about me.” The Spirit only conveys
what he has received: “He will not speak on his own; he will
speak only what he hears, and he will tell you what is yet to come”
(John 16:13). The same “chain of command” appears in John
16:15, where Jesus says, “All that belongs to the Father is
mine. That is why I said the Spirit will receive from me what he will
make known to you.”
Trinitarian
Heresies
The
Father, the Son, and the Holy Spirit are God, while being
distinguishable persons. The Son obeys the Father; and these two
persons of the Trinity send out the Holy Spirit to implement our
deliverance from sin. A defensible explanation of the Trinity will
respect all these dynamics, taking special care not to illustrate
them with misleading images or simply lapse into various forms of
polytheism. One of the earliest heresies of the church came from
Marcion, a second-century theologian who distinguished the Father of
Jesus from the supposedly vindictive God of the OT, which leaves us
with more than one God. Later came the heresies of modalism and
subordinationism (or Arianism). Modalists claimed that the persons of
the Trinity are no more than guises worn by the one person of God.
One minute God is the Father, the next he is the Son or the Holy
Spirit. Subordinationists such as Arius (died AD 336) went beyond the
functionality of the NT’s chain of command, arguing that the
Son and the Holy Spirit are not themselves God but are essentially
subordinate to him. Jehovah’s Witnesses have fallen into this
latter error, suggesting that Jesus is “a god” but not
the Creator God.
These
early heresies pressed the church to refine its understanding of the
Trinity. In his response to Marcion’s error, Tertullian coined
precise language to describe the persons of the Godhead, so that
God’s “threeness” and “oneness” are
preserved. He used the Latin term trinitas to describe the Christian
God and argued that the Father, the Son, and the Holy Spirit share
the same “substance.” The Son (also, then, the Holy
Spirit) is not simply of “like substance” (Gk.
homoiousios) with God the Father, but rather is “consubstantial”
(Gk. homoousios) with him: the Son is God, and so is the Holy Spirit.
The Nicene Creed of AD 325 incorporated this explanation and, in so
doing, also set aside the idea that either the Son or the Holy Spirit
was created by God, as the Arian heresy requires. Nicaea also
rejected adoptionism, which regards Jesus as a man whom God promoted
by endowing him with supernatural powers.
Each
of these heresies—plus, say, the strict monotheism of
Islam—attempts to relieve the tension seen among the claims
that constitute the Trinity; however, orthodox Christians will
remember that tensions and paradoxes are not automatic
contradictions. No philosopher or theologian has ever expressly
demonstrated that the Trinity entails logical nonsense, and
Christianity’s detractors carry the burden of proof in this
case. It is one thing to allege that an idea is contradictory, and
quite another thing to show with an argument that it is so. On the
positive side, the Trinity must remain a central doctrine of the
church because it affects all the others, especially the entire work
of redemption. If God is not triune, then Jesus is not God; and if he
is not God, then he cannot save us, nor can we worship him as our
Lord. The sacrifice that he offers for our sin would not, in that
case, be supremely valuable. Consider also the application to us of
what Christ has done. If the Holy Spirit is not God, then he cannot
speak for God as one who knows perfectly his thoughts and gives us
the word of God, our Bible. Scripture indicates that God is triune,
and sinners need him to be so.