Fellowship

Concise Bible Dictionary:

This in scripture is association, and having things in common. The Lord's table is where the fellowship of Christians is expressed—all there being associated in the fellowship of Christ's death. Being thus associated, proper christian fellowship is in the light of God fully revealed—the Father and the Son. The apostles specially made known the truth of this fellowship as specially given to know it (1 John 1:33That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ. (1 John 1:3)). Being brought into such association, it follows that as regards the gospel for the world, the welfare of the saints, and the maintenance of the truth, the believer has the same aims and objects before his soul as the Father and the Lord Jesus Christ have. Out of this flows the fellowship of the saints one with another (Acts 2:4242And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. (Acts 2:42); 2 Cor. 8:44Praying us with much entreaty that we would receive the gift, and take upon us the fellowship of the ministering to the saints. (2 Corinthians 8:4); Gal. 2:99And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision. (Galatians 2:9); 1 John 1:3-73That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ. 4And these things write we unto you, that your joy may be full. 5This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all. 6If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: 7But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin. (1 John 1:3‑7)). It is also called the fellowship of the Spirit (2 Cor. 13:1414The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all. Amen. <<The second epistle to the Corinthians was written from Philippi, a city of Macedonia, by Titus and Lucas.>> (2 Corinthians 13:14); Phil. 2:11If there be therefore any consolation in Christ, if any comfort of love, if any fellowship of the Spirit, if any bowels and mercies, (Philippians 2:1)). The converse of this is also true: Christians cannot consistently have any fellowship with that which is evil or which brings dishonor upon the Lord Jesus (Psa. 94:2020Shall the throne of iniquity have fellowship with thee, which frameth mischief by a law? (Psalm 94:20); 1 Cor. 10:2020But I say, that the things which the Gentiles sacrifice, they sacrifice to devils, and not to God: and I would not that ye should have fellowship with devils. (1 Corinthians 10:20); 2 Cor. 6:1414Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? (2 Corinthians 6:14); Eph. 5:1111And have no fellowship with the unfruitful works of darkness, but rather reprove them. (Ephesians 5:11)).
In some passages the A. V. has the wordCOMMUNION” for the same Greek word, with the same meaning. Thus in 1 Corinthians 10:1616The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ? (1 Corinthians 10:16), "The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?" There is an allusion to the peace offering in verse 18 to show that those who ate the sacrifice were partakers of, had communion with, the altar; hence to eat things offered to idols would be to have fellowship with demons.

From Anstey’s Doctrinal Definitions:

This is sometimes translated communion in the KJV (i.e. 1 Cor. 10:1616The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ? (1 Corinthians 10:16)). It means to be “partakers together” in that which the parties involved have in common. Believers on the Lord Jesus Christ have been brought into fellowship with the Father and the Son (1 John 1:33That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ. (1 John 1:3)), with the Holy Spirit (2 Cor. 13:1414The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all. Amen. <<The second epistle to the Corinthians was written from Philippi, a city of Macedonia, by Titus and Lucas.>> (2 Corinthians 13:14)), and with one another (1 John 1:77But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin. (1 John 1:7)). Thus, abiding together in this fellowship, God and His people have their hearts knit together in intelligent thought, aim, purpose, desire, and affection regarding all things past, present, and future. If our thoughts and ideas are not in accord with the mind of God, then we are out of communion with Him, as far as those topics are concerned.
Fellowship of this kind does not appear in Scripture until after atonement was made, whereupon God has come out to man in grace to form a relationship with believers in the light of the full revelation of truth. Old Testament saints such as Abraham had communion with God, but not in the way in which Christians know communion with God by the indwelling Spirit. H. M. Hooke said, “The first time it [fellowship] occurs in the New Testament is in Acts 2:4242And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. (Acts 2:42). Why don’t you get it before? Because until you have eternal life revealed, manifested, and until it was communicated, there could be no such thing as fellowship. How could God take people into fellowship with Himself until He put their sins away? It is not until Christ died, rose again, and went to heaven, and the Holy Ghost came down, that you get that word” (The Christian Friend, vol. 12 [1885], p. 234).
In Scripture, Christian fellowship (1 Cor. 1:99God is faithful, by whom ye were called unto the fellowship of his Son Jesus Christ our Lord. (1 Corinthians 1:9); Acts 2:42-4742And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. 43And fear came upon every soul: and many wonders and signs were done by the apostles. 44And all that believed were together, and had all things common; 45And sold their possessions and goods, and parted them to all men, as every man had need. 46And they, continuing daily with one accord in the temple, and breaking bread from house to house, did eat their meat with gladness and singleness of heart, 47Praising God, and having favor with all the people. And the Lord added to the church daily such as should be saved. (Acts 2:42‑47)) is all about togetherness. It involves being gathered “together” unto the name of the Lord Jesus Christ (Matt. 18:2020For where two or three are gathered together in my name, there am I in the midst of them. (Matthew 18:20)), coming “together” for the breaking of bread (Acts 20:77And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight. (Acts 20:7)), assembling “together” for prayer (Acts 4:31; 12:1231And when they had prayed, the place was shaken where they were assembled together; and they were all filled with the Holy Ghost, and they spake the word of God with boldness. (Acts 4:31)
12And when he had considered the thing, he came to the house of Mary the mother of John, whose surname was Mark; where many were gathered together praying. (Acts 12:12)
; Rom. 15:3030Now I beseech you, brethren, for the Lord Jesus Christ's sake, and for the love of the Spirit, that ye strive together with me in your prayers to God for me; (Romans 15:30)), assembling “together” for ministry from the Word (Acts 11:2626And when he had found him, he brought him unto Antioch. And it came to pass, that a whole year they assembled themselves with the church, and taught much people. And the disciples were called Christians first in Antioch. (Acts 11:26); 1 Cor. 14:2323If therefore the whole church be come together into one place, and all speak with tongues, and there come in those that are unlearned, or unbelievers, will they not say that ye are mad? (1 Corinthians 14:23)), assembling “together” for administrative actions (Acts 15:3030So when they were dismissed, they came to Antioch: and when they had gathered the multitude together, they delivered the epistle: (Acts 15:30); 1 Cor. 5:44In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ, (1 Corinthians 5:4)), being “together” for mutual comfort and encouragement (Rom. 1:1212That is, that I may be comforted together with you by the mutual faith both of you and me. (Romans 1:12)), walking “together” with one mind and with the same objectives (1 Cor. 1:1010Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye all speak the same thing, and that there be no divisions among you; but that ye be perfectly joined together in the same mind and in the same judgment. (1 Corinthians 1:10)), and being labourers “together” in the service of the Lord (1 Cor. 3:99For we are laborers together with God: ye are God's husbandry, ye are God's building. (1 Corinthians 3:9); 2 Cor. 6:11We then, as workers together with him, beseech you also that ye receive not the grace of God in vain. (2 Corinthians 6:1)).