I.        INTRODUCTION

A.      Despite the title, this is not a lesson about mathematics.  Instead, it is a lesson about the Lord’s church.

                                                             1.      The church is Christ’s called-out body (Gr. ekklesia).  It is comprised of all persons on earth who are saved through faith in Christ Jesus.

                                                             2.      In a local sense, the church is comprised of saved persons in a particular locality who assemble together for the purpose of worship and work in the Lord.

B.      Let us use the mathematical terms addition, multiplication, subtraction, and division to understand the growth of the Lord’s church.

II.      ADDITION

A.      It is the Lord who adds souls to His church.

                                                             1.      After Peter confessed his belief in Jesus, the Lord declared, “I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it” (Matt. 16:18).

a.       Jesus built His church on the bedrock of faith in Him.  Those who have faith that Jesus is “the Christ, the Son of the living God” (Matt. 16:16) are added by the Lord to His church.

b.       Paul said that the church is comprised of all those in Christ who are “built upon the foundation of the apostles and prophets, Christ Jesus Himself being the corner stone” (Eph. 2:19-22).  See also 1Peter 2:4-10.

                                                             2.      After the church was first established, the Scripture says, “the Lord was adding to their number day by day those who were being saved” (Acts 2:47).

a.       Specifically, the Lord added those who heard the word of God, believed it, and obeyed it (Acts 2:37-41).

b.       The Lord saves people from their sins and adds them to the church simultaneously.  To be saved is to be added to the body of the saved, the church.

c.        Notice that the Lord does not consult with men about His additions.  He alone decides who will be in His church on His terms (i.e., the gospel).

B.      It is Christians’ responsibility to add themselves to a local congregation.

                                                             1.      Christians ought not to think of the church as some abstract concept to which they belong.  They should seek others who have been added to the Lord’s church so that they can worship and work together.

                                                             2.      It is each Christian’s responsibility to assemble with a congregation of other Christians so that all may be edified together (1Cor. 11:17-34; Eph. 4:11-16; Heb. 10:23-25).

III.   MULTIPLICATION

A.      By the work of evangelism, the membership of the church will multiply.

                                                             1.      This multiplication is exemplified in the book of Acts (4:4; 5:14; 6:1, 7; 8:4, 12; 9:31; 11:21, 26; 12:24; 13:48; 14:1, 21; 16:5; 17:4, 12, 34; 18:8; 19:10, 20).  Notice especially how the spread of the word of the Lord is associated with the growth of the church:

a.       “But the word of the Lord continued to grow and to be multiplied.” (Acts 12:24)

b.       “So the word of the Lord was growing mightily and prevailing.” (Acts 19:20)

                                                             2.      The growth of the church today is still accomplished by the spreading of God’s word (2Tim. 2:2).

a.       The word of God is the seed that grows in the heart of man and gives him life.  Not every heart will accept the seed, but those who do will bear fruit (Matt. 13:1-23; 1Pet. 1:22-23).

b.       It is every Christian’s responsibility to sow the seed of God’s word, which may or may not convert others to Christ.  It is God’s responsibility to cause the growth of that seed (1Cor. 3:6).

B.      The goal of evangelism is not the multiplication of persons in attendance at worship assemblies, but rather it is the multiplication of souls that are saved in Christ.

                                                             1.      If the goal was to multiply attendance, then there are worldly means that could be used to attract more people than are attracted by the gospel.  Churches that offer entertainment and recreation typically multiply their attendance significantly, but they do not lead souls to Christ.

                                                             2.      As it is, evangelism is effective only for saving souls from sin (Rom. 1:16).  It may not gain many persons, but those whom it does gain will be saved from their sins.  The Lord said, “For many are called, but few are chosen” (Matt. 22:14).

IV.    SUBTRACTION

A.      Just as the Lord adds to His church, He also has the authority to take away from His church.

                                                             1.      Just as a Christian can forfeit his salvation because of unfaithfulness and sin (Gal. 5:4; Heb. 6:4-6; 10:26; 2Pet. 2:20-22), so also a Christian can forfeit his place in the church, which is the body of the saved.

                                                             2.      Membership in a local church does not guarantee recognition by the Lord.  It is possible for a person to hide his sin from others, but nothing will be hidden from the Lord, who will separate the sinners from the saints (Matt. 13:24-30; Heb. 4:13).

B.      There are situations when a local church must remove a member from their midst.

                                                             1.      When a Christian is engaged in sin and refuses to repent, a local congregation must cut off their relationship with him (1Cor. 5:1-13).

a.       There are two reasons for this – one is for the sake of the one who is in sin, and the other is for the sake of the church.

i.         It is hoped that the loss of fellowship with the church will provoke the sinner into repentance (v. 5; see 2Cor. 2:5-8; 7:8-10).

ii.        It is also necessary to remove the sinner’s corrupting influence from the church so that the church does not become unholy and unacceptable to Christ (vv. 6-8).  The church is better off without the sinner (“addition by subtraction”).

b.       Notice the degree to which the church must sever their relationship with the sinner.  Paul said he should “be removed from your midst” (v. 2) and that they should not even eat with him (vv. 9-11).

                                                             2.      The Lord ordained a process whereby such matters should be handled (Matt. 18:15-17).  The church must be careful to follow the Lord’s directions.

V.      DIVISION

A.      The Lord desires unity in His church, but division is sometimes necessary.

                                                             1.      The Lord prayed for the unity of His believers (John 17:20-21), but the unity for which He prayed was based upon the truthful word of God (John 17:17).

a.       Paul advised the church at Corinth not to be divided, but to “be made complete in the same mind and in the same judgment” (1Cor. 1:10).

i.         The mind and judgment in which Christians are to unite is not their own, but it is the mind of Christ which is revealed in God’s word (1Cor. 2:6-16).

ii.        Without such unity, it is impossible for a church to be complete and mature.

b.       Unity alone is not the will of Christ, but He desires unity of the Spirit (Eph. 4:1-3).

                                                             2.      When men refuse to observe the word of God, it is necessary for faithful men to divide from them.

a.       Paul wrote that divisions were necessary to separate the approved (i.e., approved of God) from the unapproved (1Cor. 11:19).

b.       Notice the command to divide: “Now I urge you, brethren, keep your eye on those who cause dissensions and hindrances contrary to the teaching which you learned, and turn away from them” (Rom. 16:17).

c.        As sad as it is, sometimes a church cannot progress until such a division occurs.

B.      The source of division in the church is those who do not hold to the word of God.

                                                             1.      Those who disturb the unity of the Spirit with the wisdom of the world are responsible for dividing the church.  They are accountable to God for defiling God’s holy temple (1Cor. 3:16-20).

                                                             2.      Many times those who stand for the truth are falsely labeled as dividers just as Ahab called Elijah a “troubler of Israel” (1Ki. 18:17).  The real blame for division belongs to those who forsake God’s word.

VI.    CONCLUSION

A.      This lesson may be overly simplistic, but it is an easy way to understand the establishment, growth, and preservation of the Lord’s church.

B.      If we will observe these simple truths, then the local church will be all that the Lord would desire.