What is a church?
I love the way the essence of the early church is encapsulated in those words from Acts 2:44:

“They were continually devoting themselves to the apostles’ teaching and to fellowship, to the breaking of bread and to prayer.”

• Apostles’ Teaching
• Fellowship
• Breaking of Bread
• Prayer

What better way to sum up what a church is all about!

And this was not just a matter of outward form. Many of the practices in the first church I joined as a teenager were like that.
But these early Christians “were continually devoting themselves to” these things. (AV, NKJV “they continued steadfastly in”)

This is really important. As the Westminster Confession puts it: “Particular churches are more or less pure” only “according as the doctrine of the gospel is taught and embraced…”[1] Where “the doctrine of the gospel is taught”, but not “embraced” in practice, that can hardly claim to be a church.

TEACHING

“They were continually devoting themselves to the apostles’ teaching”

A church is only a church as it is “built on the foundation of the apostles and prophets, Jesus Christ Himself being the chief cornerstone”[2]

The teaching must be Biblical, i.e. from the mouth of of “the apostles and prophets”.
The apostle John wrote to his hearers: “That which we have seen and heard we declare to you, that you also may have fellowship with us; and truly our fellowship is with the Father and with His Son Jesus Christ”[3]
Fellowship with other believers, and in particular “with the Father and with His Son Jesus Christ”, is only possible as we listen to what the apostles “have seen and heard [and] declare to you”.
As John goes on to say: “We are of God. He who knows God hears us; he who is not of God does not hear us.” He adds: “By this we know the spirit of truth and the spirit of error.”[4]

The teaching must be balanced.
It is not enough that what is taught is from the Bible, but over time it needs to reflect the breadth of Biblical teaching. Jesus promised the apostles: “When the Spirit of truth has come, He will guide you into all truth”[5]. Paul, in Ephesus, was able to say: “I have not shunned to declare to you the whole counsel of God.”[6] 

Faithful preaching will  be based in the gospel; but that does not mean it will be just a series of evangelistic messages Sunday by Sunday. But this is a common failure in much preaching today– as it was back when the apostle wrote Hebrews:

“We have much to say, and hard to explain, since you have become dull of hearing. For though by this time you ought to be teachers, you need someone to teach you again the first principles of the oracles of God; and you have come to need milk and not solid food… Therefore, leaving the discussion of the elementary principles of Christ, let us go on to perfection, not laying again the foundation of repentance from dead works and of faith toward God…” etc[7]

And, not only did Paul preach all the truth, he made sure he didn’t avoid aspects of truth that were needful at the time: “I kept back nothing that was helpful.”[8]
As Martin Luther is alleged to have put it:

“If I profess with loudest voice and clearest exposition every portion of the truth of God except that little point which the world and the Devil are at that moment attacking, I am not confessing Christ, however boldly I may be professing Christ. Where the battle rages, there the loyalty of the soldier is proved, and to be steady on all the battlefield besides, is mere flight and disgrace if he flinches at that point.”

There are two areas I have observed many preachers neglect today:

1) Cultural sacred cows. I am thinking of issues such as sexuality and gender, or creation and evolution – issues which underlie, or are addressed in, teaching in nearly every book of the Bible, but which are often bypassed by faint-hearted preachers in dealing with such passages. Such men are not “not confessing Christ, however boldly [they] may be professing Christ.”

2) The Trinity. Trinitarian theology lies at the heart of “the whole counsel of God”.[9] Yet, today, while many preachers rightly proclaim that “at the name of Jesus every knee shall bow and every tongue should confess that Jesus Christ is Lord”, few bother to finish the text: “to the glory of God the Father.”[10] So much teaching in churches today is Sabellian theology that focuses on “Jesus only”, ignoring God the Father and God the Spirit.[11]

The teaching needs to be personal.
“The apostles’ teaching” refers to the act of live instruction, not just the content of what was taught. “Clearly, the latter was the goal of the former. But the text focuses on the enthusiasm of the people for sound preaching and teaching.”^[12]
It was not a matter of reading something the apostles had given you to take home and read; it was not a matter of watching them on a screen in a multi-site church, much less on a screen at home (unless prevented from attending, eg. by sickness – or a pandemic!) No, the people were “continually devoting themselves” to being present where the apostles were teaching face to face.
Paul taught those in Ephesus personally, both “publicly and from house to house”^[13] He cared for those in Thessalonica “as a nursing mother cherishes her own children”, and “exhorted, and comforted, and charged every one as a father does his own children”^[14]

See also: What is a Preacher?

FELLOWSHIP

“They were continually devoting themselves to fellowship”.
As with preaching, such fellowship is best practised face to face.[15]

The basis of fellowship:
As John tells us (above), We can only have fellowship with one another as “truly our fellowship is with the Father and with His Son Jesus Christ”[16]
Those who were “continually devoting themselves to fellowship” were those “who gladly received his word were baptized”[17] For “what fellowship has light with darkness?”[18]

But how can we know who are God’s children?
Jesus said “by their fruits you will know them.”[19] What fruit? An important fruit we look for, is that those in the church want to listen to, and shape their lives by, the Word of God.[20]
In practice, this will be evident in an obvious desire to lead a holy life. Not perfect, for none are perfect this side of heaven (and we need to be ready to forgive as we ourselves are forgiven). But God’s children are marked by a genuine pursuit of holiness.[21]

The fruit of love:
Perhaps nothing so distinguishes the children of God as the love they have for one another. “By this all will know that you are My disciples, if you have love for one another.”[22] 
I cannot emphasise this too strongly. From the moment a new believer sets foot in a church, nothing will convince him he is in the right place so much as the loving welcome he receives.[23] Where that is absent, he is unlikely to return – and for good reason.
Love is expressed in hospitality.[24] “All church members should ask themselves, ‘How often do I invite anyone home for meals or coffee?’ and, ‘What kind of people do I ask to my home? Are they only those who are well off enough to ask me back?’”^[25]

The early church practiced fellowship (Gk. koinonia) by sharing: “All who believed had all things in common [Gk. koinos], and sold their possessions and goods, and divided them among all, as anyone had need.”[26]

WORSHIP

“They were continually devoting themselves to the breaking of bread”
A common meal? Or the Lord’s Supper as part of worship?
Most commentators agree that “the context seems to suggest that it refers to a celebration of the Lord’s Supper.”[27]

Elsewhere, Paul had something to say about the need for reverence in the conduct of the Lord’s Supper.[28] But the same is true for the whole of worship.
The early disciples worshipped; they were “continuing daily with one accord in the temple”[29] Their worship was marked by unity (“with one accord”) and reverence (“fear came upon every soul”[30]), and joy.[31]
Don’t go to a church where, in “worship”, reverence and joy have given way to entertainment (see here).

Also, worship in the New Testament was Trinitarian[32] – unlike I find in many churches today that openly say they worship “Jesus only”. Let me be clear that I rejoice to worship Christ Jesus “who loved me and gave Himself for me.” And I rejoice “because the love of God has been poured out in our hearts by the Holy Spirit who was given to us.”

Again, see here.

PRAYER

“They were continually devoting themselves to prayer”

Before Pentecost, the early church was born in a prayer meeting: “These all continued [same word as in Acts 2:42] with one accord in prayer and supplication…”[33]
And they never gave up meeting together to pray.[34]

Likewise the apostles never gave up exhorting church members to be meeting together for prayer:

• “Continue steadfastly in prayer”[35],
• “You also help together in prayer for us”[36],
• “Pray always with all prayer and supplication in the Spirit”[37],
• “Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God”[38],
• “Continue earnestly in prayer, being vigilant in it with thanksgiving”[39],
• “Pray without ceasing”[40],
• “Pray for us, that the word of the Lord may run swiftly and be glorified”[41],
• “Let supplications, prayers, intercessions, and giving of thanks be made for all men”[42],
• “Let the elders of the church pray over the sick”[43],
• “Be serious and watchful in your prayers”[44]
• “Keep yourselves in the love of God” by “praying in the Holy Spirit” ^[45]

Prayer is vital to the life of the church.
“Brethren, we shall never see much change for the better in our churches till the prayer meeting occupies a higher place in the esteem of Christians.” (C. H. Spurgeon)
See also here. And here, here and here

A church whose members show little enthusiasm to meet together for prayer cannot expect to prosper (unless you are measuring “prosperity” in purely worldly terms).

WITNESS

Finally, there is the church’s witness.

Where the life of a church is defined by: Teaching, Fellowship, Worship, Prayer – such a church has life, spiritual life. And a church with spiritual life will be a living witness in the community.

We read of the early church that they were “praising God and having favour with all the people.” And what happened?
“The Lord added to the church daily those who were being saved.”[46]

Their witness was, first and foremost, in their very life: they “had favour with all the people”.
Their care for one another, and the holy lives they lived, were an irrefutable witness to the power of the gospel in their lives.
“The best sermon ever preached is a holy life. If you want others to serve God, serve him yourself.” (DeWitt Talmage) “Pure and undefiled religion before God and the Father is this: to visit orphans and widows in their trouble, and to keep oneself unspotted from the world.”[47]

But those who “walk in wisdom toward those who are outside, redeeming the time”, will also see that “[their] speech is always with grace, seasoned with salt, that [they] may know how [they] ought to answer each one.”[48] We preach first with our lives, secondly with our mouths.
Those in the early church did so.
When threatened, they prayed all the more “that with all boldness we may speak Your word”; and God answered so that “they were all filled with the Holy Spirit, and they spoke the word of God with boldness.”[49]
When those threats materialised, and the early Christians began to be killed off, undeterred “those who were scattered went everywhere preaching the word”[50].

• Teaching
• Fellowship
• Worship
• Prayer
• Witness

That is a church!

[1] Westminster Confession ch 25, § 4
[2] Eph 2:20
[3] 1 Joh 1:3
[4] 1 Joh 4:6
[5] Joh 16:13
[6] Act 20:27
[7] Heb 5:11-6:1. See also Eph 4:11-13
[8] Act 20:20
[9] Eg. Matt 28:19, Luke 3:22, Joh 17:3, 1 Cor 8:6, 2 Cor13:14 etc
[10] Phil 2:10–11
[11] See futher: http://transformingourconforming.com/how-do-you-solve-a-problem-like-maria/
[12] G. J. Keddie, You Are My Witnesses: The Message of the Acts of the Apostles
[13] Acts 20:20
[14] 1 Thes 2:7, 11
[15] Heb 10:24-25
[16] 1 Joh 1:3
[17] Acts 2:41
[18] 2 Cor 6:14
[19] Matt 7:20
[20] Joh 10:27, 1 Joh 4:6
[21] Heb 11:14
[22] Joh 13:35
[23] Jas 2:1-4, Cf Acts 9:26-27
[24] Rom 13:13, Heb 13:2
[25] M. Bentley Saving a Fallen World: Luke Simply Explained Luke 3:11. See also Jas 2:1-4
[26] Acts 2:44–45. See also Acts 4:32-37, Jas 1:26-27, Jas 2:14-17, 1 Joh 3:16-19
[27] S. J. Kistemaker & W. Hendriksen Exposition of the Acts of the Apostles
[28] 1 Cor 11:17-22
[29] Acts 2:46a
[30] Acts 2:43
[31] Acts 2:46b-47
[32] cf Phil 3:3. Also, before: Matt 28:19, Luke 3:22, Joh 17:3, 1 Cor 8:6, 2 Cor13:14 etc. And: Gal 2:20, Rom 5:5
[33] Acts 1:14
[34] See: Acts 1:24-25, 2:42, 4:23-31, 12:5, 13:1-3, 14:23, 16:25, 20:36, 21:5 etc
[35] Rom 12:12
[36] 2 Cor 1:11
[37] Eph 6:18
[38] Phil 4:6
[39] Col 4:2
[40] 1 Thes 5:17
[41] 2 Thes 3:1
[42] 1 Tim 2:1
[43] Jas 5:14
[44] 1 Pet 4:7
[45] Jude 20–21
[46] Acts 2:47
[47] Jas 1:27
[48] Col 4:5-6. Cf 1 Pet 3:15
[49] Acts 4:29-31
[50] Acts 8:4