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How Firm a Foundation

September 20, 2020

Teacher: Daniel Baker
Scripture: Ephesians 2:20


You may have noticed the four panels on the blue wall across the lobby: Big prints that say Doctrine, Spirit-filled, Relationships, Spiritual Growth. In smaller words beneath these titles the first two say “Our Foundation” and the next two say “Our Mission.”

As talk about the DNA of Cornerstone over these four weeks, we’re talking about these four things. It’s who we are. To some extent it’s even who God has made us to be.

This morning we start with “Doctrine.” The simplest definition of “doctrine” is “something that is taught,” a “teaching.” The Greek words behind it in the NT either refer to the act of teaching or what is actually taught.

And you can have doctrine that is strong and healthy and right. Or you can have doctrine that is unhealthy and wrong.

We want to follow what the apostle Paul commanded Titus to do:

But as for you, teach what accords with sound doctrine. (Titus 2:1)

“Sound” here means “healthy” or “free from error, correct.” Throughout Paul’s letters to Timothy and Titus, he refers often to “sound doctrine.” Elders and churches are called by God to “teach what accords with sound doctrine.”

Paul isn’t commanding the church to teach only complicated theological ideas that only trained theologians can understand. He’s commanding the church to teach only what is true and to teach the true things that are truly important.

Paul’s command is just another way of saying to teach the Bible and teach what is true as defined by the Bible.

Healthy doctrine is what leads to healthy Christians and healthy churches. When a church’s doctrine becomes unhealthy or unsound, it produces unhealthy Christians that build unhealthy churches. The church might be big and influential for a time, but eventually the weakness and disease in it will be clear.

Ephesians develops a picture of sound doctrine and why it’s so important for each of us and for the church.

It speaks of God’s inspired truth as a FOUNDATION for the church. A foundation the church can build on.

Here’s our main passage for this series:

So then you are no longer strangers and aliens, but you are fellow citizens with the saints and members of the household of God, 20 built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone, 21 in whom the whole structure, being joined together, grows into a holy temple in the Lord. (Eph 2:19–21)

In the DNA of Cornerstone is a deep desire to be “build on the foundation” God has laid in his Word.

And Ephesians shows us this foundation provides five things we can’t find anywhere else:

  • Knowledge of God
  • Message of Salvation (1:13–14)
  • Rule of Life (4:25–26)
  • Means of Transformation (4:15–16)
  • Equipment for Battle (6:10–17)



I. Knowledge of God

One of the most glorious aspects of God’s truth is that it gives us a knowledge of God himself. God as Father, Son, and Holy Spirit. This is the God that leaps off every page and almost every sentence of Ephesians.

First he is God the Father:

  • In chapter one, he is the “Blessed” one, the “one to be praised” (1:3; L&N)
  • He is the God who chose us before the foundation of the world according to his good pleasure (1:4)
  • The God working all things according to his own will (1:11)
  • The Father of Glory (1:17)
  • In chapter three, he’s “able to do far more abundantly than all we ask or think, according to his power at work within us” (3:20)
  • That’s God the Father!

Then he is God the Son:

  • In chapter one, he is the Son of God the Father (1:3); “the Lord”: God himself; the promised Messiah (1:2)
  • It’s through him we have been redeemed since it is Jesus the Son who shed his blood on our behalf (1:7)
  • And then at the end of chapter one Paul prays a glorious prayer. And in it he prays we would “know” (v. 18) God’s power. Here’s how he describes that power:

[I pray that you may know] what is the immeasurable greatness of his power toward us who believe, according to the working of his great might 20 that he worked in Christ when he raised him from the dead and seated him at his right hand in the heavenly places, 21 far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in the one to come. (Eph 1:19–21)

  • There’s only one who was raised from the dead and then ascended to God the Father’s right hand—Christ Jesus!
  • Only one who stands not just “above” but “far above” all rulers—Christ Jesus!
  • In a culture like Rome where you’re surrounded by subtle and not so subtle depictions of Rome as eternal and dominant, Paul wasn’t fooled.
  • Jesus is greater, Jesus is the King, Jesus is the true Lord
  • But then in chapter three, Paul prays that we would know the love of Christ that is beyond comprehension, that we would know the “breadth and length and height and depth” of Christ’s love and so be “filled with all the fullness of God” (3:17–19).

Then he is God the Spirit:

  • The Spirit in Ephesians is connected to our life at every point.
  • When we were saved we were “sealed” by the Spirit (1:13), marked as God’s own, indicated to be the genuine article.
  • The Spirit in chapter one is “the guarantee of our inheritance” (1:14)—the down payment we get to experience now as we wait for the full experience later.
  • In chapter two it is through the Spirit we have access to the Father (2:18) and the church becomes the very dwelling place of God himself (2:22).
  • In chapter three it is the Spirit that Paul prays for so that we would have the power to grasp Christ’s love.

These are things we simply couldn’t know about God without his Word. These aren’t human insights or Paul by the fireside saying, “I like to think of God like this, how do you guys like to think about God?”

The greatest benefit of having a foundation of sound doctrine is being introduced to the true and living God as he truly is. Not how we imagine him to be. The God of reality. In Francis Schaeffer’s words, “The God Who is There.”

The God you can know and who knows you. In the words of Rich Mullins, he’s the God “too good to be real, but is more real than the air we breath.”[1]

II. Message of Salvation (1:13–14)

Ephesians 1:13–14 also reminds us of something else we get in this foundation of God’s Word, something we find nowhere else.

Ephesians 1:13–14:

In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, 14 who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory. (Eph 1:13–14)

When a church builds on the right foundation it has “the word of truth, the gospel of your salvation.”

The gospel is the good news that Jesus the Son of God came to die for our sins and promises forgiveness for our sins for all who believe in him. This is “the gospel” that:

  • Brings forgiveness for all our sins (1:7)
  • Brings our dead souls to life (2:1–5)
  • Takes us from being far away from God and gives us access to go near to him (2:18)

The gospel doesn’t promise easy street or a pain-free life—might be just the opposite. But it does promise eternal life and forgiveness and a reconciled relationship with the living God.

It’s easy to take “the word of truth, the gospel of your salvation” for granted. But church history is filled with Christians and churches that lost their grip on it. They let other things crowd it out.

Other things became more important than this “word of truth.” Maybe some cause of the day.

Or, they changed this word of truth to make it more acceptable to the culture around them. At times it was minimizing the seriousness of sin. At other times it’s saying there are other messages that offer “the gospel of your salvation.”

III. Rule of Life (4:25–26)

Reformed Puritans had a way of referring to God’s commandments. For believers God’s commandments are a “Rule of Life.”[2] For believers, obedience to God’s commandments is not how we’re either “justified or condemned.” But God’s commands are a rule of life showing what God wants of us in how we live our lives.

In Ephesians 4:25–26 we see it in action.

Therefore, having put away falsehood, let each one of you speak the truth with his neighbor, for we are members one of another. 26 Be angry and do not sin; do not let the sun go down on your anger. (Eph 4:25–26)

Why these verses? Because Paul does something here we want to notice. He quotes from two OT passages to teach us as Christians how to live. In 4:25 he quotes from Zechariah 8:16. In 4:26 he quotes from Psalm 4:4.

That tells us the OT has commands binding for us as Christians. The NT speaks directly to us as a “Rule of Life.” But the OT, too, also teaches us. Paul here quotes directly from the OT without any qualification.

This doesn’t mean that every commandment in the OT speaks as directly as these two. But it does show us that in the OT and NT there are divinely inspired commandments that show us God’s will for our behavior.

In these two verses Ephesians speaks to our truth-telling and sinful anger. But the rest of Ephesians speaks to a whole range of topics—personal holiness, sexuality, how a husband and a wife should relate, parenting, how to act in the workplace, life in the church.

God’s will extends to all areas of our lives. Our thoughts, emotions, deeds, relationships, use of money. He cares about how we live our lives.

We tend to think of “sound doctrine” as dealing with complex theology. At times it does. But “sound doctrine” also means speaking rightly about how we are to live. As a quick illustration we can look at the verse from Titus 2 we read earlier.

Titus 2:1–2:

But as for you, teach what accords with sound doctrine. 2 Older men are to be sober-minded, dignified, self-controlled, sound in faith, in love, and in steadfastness. (Titus 2:1–2)

Do you see that? Right after mentioning “sound doctrine” he launches into a section on what “older men” are to do and to be.

Maybe the application of this sermon on sound doctrine for you is right here. Are you an “older man”? “Well, that all depends…” Are you? This is the kind of man God commands you to be.

IV. Means of Transformation (4:15–16)

A fourth thing we learn about sound doctrine in Ephesians is that it has the power to change us.

Ephesians 4:15–16:

Rather, speaking the truth in love, we are to grow up in every way into him who is the head, into Christ, 16 from whom the whole body, joined and held together by every joint with which it is equipped, when each part is working properly, makes the body grow so that it builds itself up in love. (Eph 4:15–16)

Right before this Paul had mentioned the impact of lies and schemes on the people of God. When we turn to these we’re battered about. Like adrift at sea, subject to the wind and waves (Eph 4:14).

In contrast to that we are to “speak truth in love.” Truth or sound doctrine or God’s Word is what we speak to one another. And the result is growth.

The Greek is really saying, “BY MEANS OF speaking the truth in love, let us grow up in every way.”[3]

God’s Word, God’s truth, this is part of what God uses to help us grow. When people motivated by love speak God’s truth to us, growth happens. We grow more and more conformed to the image of Christ.

The image here is a developing and maturing body that has left childhood and is moving toward being a fully developed person. We become more mature by timely and loving truth spoken to us by others in our lives.

The hard part is knowing which truth in the moment is the timely and loving truth!

The point here is that our foundation in sound doctrine is closely connected to our commitment to spiritual growth. When anyone comes into the community of the church, our desire is to see them grow.

See them become what God wants them to be. Walk in their gifting. Mature in their character. Grow in their knowledge of God and relationship with God.

That kind of change requires that we’re “speaking truth in love” to one another in strategic ways—whether it’s Sunday morning or a class or in a conversation.

V. Equipment for Battle (6:10–17)

For our last point we change from the image of a developing human body to a battlefield. A war. God’s Word is a key part of what equips us for the battles we fight as Christians.

Ephesians 6:10–17:

Finally, be strong in the Lord and in the strength of his might. 11 Put on the whole armor of God, that you may be able to stand against the schemes of the devil. 12 For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. 13 Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm. 14 Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, 15 and, as shoes for your feet, having put on the readiness given by the gospel of peace. 16 In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; 17 and take the helmet of salvation, and the sword of the Spirit, which is the word of God. (Eph 6:10–17)

Paul reminds us we live “in the evil day.” And “in the evil day” we fight against enemies—not ones that are “flesh and blood.” But “spiritual forces of evil.”

But the Lord hasn’t left us unprotected and unable to fight. He’s given us “the whole armor of God.”

Look, though, at this “armor of God.” No grenades or rocket-launchers in this arsenal:

  • The armor that we’re given starts with “the belt of TRUTH” (verse 14).
  • Then comes the “breastplate of righteousness” (verse 14).
  • Then feet rooted in GOSPEL TRUTH[4] (verse 15) and protected by a “shield of faith” (verse 16).
  • Then we take our “helmet of salvation” (verse 17).
  • Finally, “the sword of the Spirit, which is the WORD of God” (verse 17).

Our defensive armor is everywhere connected to God’s truth and believing and living out his truth.

Our one piece of offensive weaponry is God’s truth, his very word. This is what we take up and use to damage and destroy and attack the lies of the devil and the devil himself.

Sound doctrine is not the stuff of dusty bookshelves in forgotten libraries. It’s what you find in an armory. It’s what you’re handed by your commanding officer as you’re about to step into the field of battle. It’s what you need to wage the battles of your life.


Our foundation that leads to mission…

The Word at CFC:

  • What is Taught
    • Sunday morning sermons, children’s ministry, Bible studies
  • What is Believed and Obeyed
    • As its taught, we respond. Believe it. Obey it.
  • What is Sung
    • Our songs to saturated with truths from the Bible. Sometimes song lyrics are taken directly from Scripture. All the time we want the words that we sing to be entirely consistent with the truth in God’s Word.
  • What is Transferred
    • As in 4:15, “speaking the truth in love” to one another.

But this is a truth we need to MAKE PERSONAL.

  • The backbone of growing in sound doctrine is being faithful in reading your Bible.
  • The day-in, day-out, week-in, week-out reading of your Bible is a powerful way to help you make “the sword of the Spirit” battle ready for you.

Two things to help you with that:

  • Journal—a gift to you!
  • Cornerstone Readers – beginning Oct 1st

John Norcott (d. 1676) was a 17th Calvinistic Baptist. He wrote an early and widely read defense of believer’s baptism. 17th century not a time when being a Baptist won you any popularity contests. Norcott was jailed several times for living out his Baptistic convictions, along with John Bunyan and many others. But John Norcott was persuaded by God’s Word of the truth of believer’s baptism. A contemporary of his, William Kiffen, in the preface to Norcott’s work, said this:

He steered his whole course, by the compass of the Word, making Scripture-precept, or example, his constant rule in matters of religion: Other men’s opinions or interpretations were not the standard by which he went; but, through the assistance of the Holy Spirit, he laboured to find out what the Lord himself had said in his Word. 
William Kiffen, “Preface,” Baptism Discovered[5]

Prayer and closing song


[1] Rich Mullins, “What Susan Said.”

[2] See WCF 19.6 (and current TFC COF 19.6 as well).

[3] Thielman, BECNT, 285.

[4] Cf. Thielman, BECNT, 426.

[5] Cited in Haykin, Kiffen, Knollys, and Keach, 100.

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