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The God We Worship: “Unity in Trinity and the Trinity in Unity”


Text: 1 Peter 1:1-2
Readings: Genesis 1:1-5; 1 Peter 1:1-11; Heidelberg Catechism Lord’s Day 8

August 17, 2014 • Download this sermon (PDF)


Congregation of Christ: The doctrine of the Trinity is foundational to the Christian faith. But it is also very deep that the history of the church—even today—is marked by controversies regarding this doctrine.

Therefore, one of the most frequently asked questions among families and churches is, How do we teach this doctrine to our young children, when even adults have a hard time understanding it? If God is three, then Christianity is no different from pagan religions with many gods. If God is one, then how can Christ be also God? There is One God, but Three Persons in this One Godhead. This is a great mystery. The 6th century Athanasian Creed (named after the great 4th century theologian Athanasius) calls this mystery, “Unity in Trinity and the Trinity in Unity.”

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The most common method is to illustrate the Trinity with analogies from nature, such as the three parts of an egg, the three states of water, a three-layered cake, or the three-fold role of a working man: husband, father, employee. But these analogies have only led many pastors and teachers into teaching an ancient heresy called modalism. Modalism teaches that God is one Person appearing in three “modes” or “aspects” or “manifestations”: God the Father in the Old Testament, God the Son in the New Testament, and God the Spirit after he ascended back into heaven.

Modalism is only one of many heresies which have plagued the church since the beginning. The 2nd-3rd century church apologist Tertullian was the first to use the word “Trinity” and explain it in great detail. He did not invent the doctrine, but only expounded it to defend it against those who taught different doctrines. He also gave us two words that are still very crucial today in our discussions: “person” and “substance.” Those who don’t believe this doctrine argue that the word “Trinity” is not in the Bible. This argument is very shaky, because there are many doctrinal words that are not in the Bible, such as “incarnation” and “Lord’s Supper.”

The Heidelberg Catechism Lord’s Day 8 deals with this subject in its introduction to the Apostles’ Creed. This ancient ecumenical creed divides the Christian faith into three parts according to the Trinity. It is a simple declaration of the doctrine of the Trinity: that the God we worship, the God of the Old and New Testaments, is one God in Three Persons. And these Three Persons are distinct in their roles in the redemption of the elect.

The Scripture is rich with this doctrine. Our text, a Trinitarian greeting in 1 Peter 1:1-2, is one of a host. Peter says that Christians are elect “according to the foreknowledge of God the Father, in the sanctification of the Spirit, for obedience to Jesus Christ and for sprinkling with his blood.”

This afternoon we will study this very important foundational doctrine, The God We Wor-ship: “Unity in Trinity and the Trinity in Unity,” under four headings: first, God the Creator; second, God the Redeemer; third, God the Sanctifier; and fourth, God the Three-in-One.

God the Creator

Before we begin studying these Three Persons and their distinct Person-ality and work, remember that they work in harmony and unity in purpose in creation, redemption and sanctification of man. These Three Persons are all involved with distinct roles in whatever this one God is doing. We will expand on this in the fourth and last point.

The First Person of the Trinity is often referred to in Scriptures simply as “God” or “Father,” or “LORD God.” In most of the Old Testament, he is called “God” or “LORD God,” the Creator who speaks the world into existence, For he spoke, and it came to be; he commanded, and it stood firm” (Psa 33:9; see also Gen 1).

God is often referred to in the singular, for example, “You shall not take the name of the LORD thy God in vain” (Exo 20:7). In the great shema, (“hear”) of Israel, God is one, “Hear, O Israel: The LORD our God, the LORD is one” (Deu 6:4). Notice also that in the Great Commission, Jesus commanded the apostles to baptize disciples “in the name of the Father and of the Son and of the Holy Spirit” (Mat 28:19). The word “name” is singular.

But often in the Old Testament, “God” is in the plural (Elohim), to indicate that he is powerful to the nth degree. God is also called the “Father” of his people in the Old Testament, such as, “Father of the fatherless and protector of widows is God in his holy habitation” (Psa 68:5). And, “O LORD, you are our Father; we are the clay, and you are our potter; we are all the work of your hand” (Isa 64:8). Messianic Psalms also call God the Father of the Messiah, “He shall cry to me, ‘You are my Father, my God, and the Rock of my salvation’” (Psa 89:26).

In the New Testament, God is also often referred to as a Father. As God the Father, he is also Creator, “for there is one God, the Father, from whom are all things and for whom we exist” (1 Cor. 8:6). And, “I bow my knees before the Father, from whom every family in heaven and on earth is named” (Eph 3:14-15). God is also the Father of his people Israel, “When Israel was a child, I loved him, and out of Egypt I called my son” (Hos 11:1; see also Exo 4:22). Jesus referred to God often as his Father, as in John 5:17, “But Jesus answered them, “My Father is working until now, and I am working” (see also John 1:14, 18; 8:54; 14:12, 13).

As Creator, God is sovereign over all his creation, “Let all the earth fear the LORD; let all the inhabitants of the world stand in awe of him!” (Psa 33:8). As Creator of mankind, he is Sovereign over all of them, “he who fashions the hearts of them all and observes all their deeds” (Psa 33:15).

Since God is our Creator, all of us creatures are accountable to him. Do you acknowledge, worship and obey him as your Sovereign Creator God, Lord and King?

God the Redeemer

Our text also says that all of God’s people are “elect exiles… according to the foreknowledge of God the Father.” Paul blesses “the God and Father of our Lord Jesus Christ… even as he chose us in him before the foundation of the world” (Eph 1:3-4). In eternity past, before there was time, God already chose whom he will save from among the sinful people of the world. He will redeem them from sin, adopt them as his own children, and give them their eternal inheritance.

How are God’s chosen ones to be redeemed? Only through “sprinkling with [Christ’s] blood.” This refers to Christ’s atoning sacrifice on the cross, when he shed his blood for the forgiveness of the sins of the elect. Sprinkling with blood to atone for sins points us back to Israel’s covenant with God at Mount Sinai when Moses sprinkled the blood of sacrificial animals on both the altar and the people (Exo 24:3-8), saying, “Behold the blood of the covenant that the LORD has made with you in accordance with all these words” (Exo 24:8). In the Lord’s Supper, we remember Jesus’s words of institution, as the fulfillment of Moses’s covenant ratification, “for this is my blood of the covenant, which is poured out for many for the forgiveness of sins” (Mat 26:28).

In the Old Testament, the LORD is called Israel’s Redeemer, especially when speaking about the Exodus from Egypt, “O Israel, hope in the Lord! For with the Lord there is steadfast love, and with him is plentiful redemption. And he will redeem Israel from all his iniquities” (Psa 130:7-8; see also Psa 111:9; Isa 41:14). The psalmist calls the LORD his Rock and his Redeemer (Psa 19:14). Job looks forward to the day of his resurrection, “For I know that my Redeemer lives, and at the last he will stand upon the earth” (Job 19:25).

Christ has redeemed us, the elect people of God, from sin and Satan. He has paid the ransom for us (1 Tim 2:5-6) through his perfect life and sacrificial death in the breaking of his own body and shedding of his own blood. Paul says, “He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, in whom we have redemption, the forgiveness of sins” (Col 1:13-14). Therefore, we can now “draw near [to God] with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water” (Heb 10:22). When he offered himself on the cross, Jesus is “the mediator of a new covenant, and to the sprinkled blood” (Heb 12:24).

God the Sanctifier

In his Trinitarian greeting, Peter also mentions the Holy Spirit as the Sanctifier, “in the sanctification of the Spirit.” What is sanctification? The word has the same root as “holiness.” It refers to the setting apart of believers in Christ, so that they are holy and righteous in the sight of God. It also refers often to the gradual holiness worked out by Spirit in the believer.

Sanctification eventually refers to “obedience to Jesus Christ.” True believers have no other result in their life except holy and righteous lives, obedient to Christ’s commandments. Jesus even said, “If you love me, you will keep my commandments” (John 14:15). The apostle John repeats his Master’s teaching, “And by this we know that we have come to know him, if we keep his commandments”(1 John 2:3).

Gentiles are now also acceptable because they are “sanctified by the Holy Spirit” (Rom 15:16). We ought to be thankful to God because he chose us to be saved “through sanctification by the Spirit and belief in the truth” (2 Thes 2:13).

But why do we call the Holy Spirit also God, the Third Person of the Godhead? In the early church, the modalists denied this. During the Reformation, the Socinians did. In the modern era, Schleiermacher, the Unitarians, and many others also rejected the Person-ality of the Spirit, saying that the Spirit is but the “power” or “influence” of God. But the Bible attests to this truth in many places. He is called the “Comforter” or “Helper.” He has intelligence and emotions. He searches, speaks, witnesses, creates, mediates. The divinity of the Holy Spirit will be discussed in detail later in Lord’s Day 20 .

God the Three-in-One

As mentioned above, the Three Persons of the Trinity work together in harmony and unity in purpose in creation, redemption and sanctification of man. They are all involved with distinct roles in whatever this one God is doing.



In creation, it was not only the Father who was working. The eternal Son of God was the Word through which the world was created. He spoke the Word into existence. Genesis 1:1 and John 1:1 states that the Word was with God in the beginning. Paul makes this very clear:

He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him (Col 1:15-16).

What most evangelicals forget is that the Spirit was also present in creation, “And the Spirit of God was hovering over the face of the waters” (Gen 1:2). The word “hovering” is used for birds who hover over their young to protect them, just as the cloud and fire, symbolic of the Spirit, guarded Israel in their wilderness pilgrimage. And the Spirit of God gave breath to Adam and Eve. Life then starts with God’s Spirit breathing life into lifeless creatures, “The Spirit of God has made me, and the breath of the Almighty gives me life” (Job 33:4; see also Psa 104:30). This is why the Nicene Creed calls the Spirit as “the Lord and Giver of Life.” You can be assured that God is with you, because “the Spirit of glory and of God rests upon you” (1 Pet 4:14).

What about redemption? How is it the work of the Triune God? We have mentioned that God elected his people even before he created the world. Then, in the fullness of time, he sent his Only-Begotten Son to offer himself as sacrifice to God for the sins of God’s elect. And the Holy Spirit makes sure that all of God’s elect are converted, given new hearts and souls, and made into God’s holy and righteous image throughout their lives, and sealed for the day of redemption. This is why the Holy Spirit is also called God, the Third Person of the Trinity.

Even the work of sanctifying his people unto holy and righteous lives is attributed not only to the Spirit, but to God and to his Son. YHWH commanded Israel to keep his Sabbaths, “that you may know that I, the LORD, sanctify you” (Exo 31:13). Jesus himself prayed to his Father, “Sanctify them in the truth; your word is truth” (John 17:17). “Now may the God of peace himself sanctify you completely” (1 Thes 5:23).

As Sanctifier, Jesus died for his church, “Jesus also suffered outside the gate in order to sanctify the people through his own blood” (Heb 13:12). Paul says that Christ Jesus “became to us wisdom from God, righteousness and sanctification and redemption” (1 Cor 1:30). The Apostle makes it clear that the Triune God work together in our sanctification. As Sanctifier, Jesus died for his church “that he might sanctify her, having cleansed her by the washing of water with the word” (Eph 5:26), “water” being a reference to the Spirit. And from eternity past, God has foreordained his elect to good works, “For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them” (Eph 2:10).

The Athanasian Creed therefore summarizes this great, foundational Christian doctrine:

We worship one God in Trinity, and Trinity in Unity; neither confounding the Persons, nor dividing the Substance. For there is one Person of the Father, another of the Son, and another of the Holy Ghost. But the Godhead of the Father, of the Son, and of the Holy Ghost, is all one, the Glory equal, the Majesty co-eternal.

The doctrine of the Trinity is what separates the Christian faith from all other religions of the world. Without the Trinity, there is no Christianity. This is why the Athanasian Creed opens with the declaration:

Whosoever will be saved, before all things it is necessary that he hold the catholic [universal] faith; which faith except every one do keep whole and undefiled, without doubt he shall perish everlastingly. And the catholic faith is this: That we worship one God in Trinity, and Trinity in Unity.

If anyone does not believe this doctrine, he is not a Christian.


Dear Chosen Ones of God: Our study today is only a brief summary of what we will be discussing in more detail in the next few weeks. But isn’t this introduction to the doctrine of the Trinity a great assurance to us?

Our Triune God is in perfect harmony and unity not only in creating us, but also in redeeming us. His redemption plan from before creation is perfect. Not only is it perfect, but it is also sure to be fulfilled. The Sovereign King does as he wills, and all his works are righteous. Therefore, our eternal salvation is assured since his plan is the unified, harmonious plan of the Trinitarian God.

Let us therefore give our Triune God all the praise and thanksgiving. There is nothing worthy in us that he should redeem us from sin and eternal death. But Christ, even while we were still sinners, died for us.

This is our song, “The LORD has remembered us; he will bless us … he will bless those who fear the LORD, both the small and the great” (Psa 115:12-13).

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