Fellowship 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 1:3.) 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 2:42; 2 Cor. 8:4; Gal. 2:9; 1 John 1:3-7.) It is also called the fellowship of the Spirit. (2 Cor. 13:14; Phil. 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. 94:20; 1 Cor. 10:20: 2 Cor. 6:14; Eph. 5:11)
In some passages the Authorized Version (KJV) has the word "communion" for the same Greek word, with the same meaning. Thus in 1 Cor. 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. Concise Bible Dictionary