Love of the divine kind isn't found in nature, but on Calvary. Love of the human kind reciprocates love, but divine love takes the initiative. God demonstrated His love for us when Christ died in our stead while we were still sinners (Rom.5:8), in order to give us life through His death, and this is the proof of His love. This is the kind of love to be revealed in us, if we are His children.
Believers ought to love one another with the same kind of love with which God loves us: it is not physical attraction, nor sentimental or social love. It is supernatural, made real only by the Spirit of God, and only He enables us to extend this love to other brethren. It isn't the kind of love we extend to brethren with whom we like to live with. There are some brethren who are little loveable from the human point of view, but in spite of this the love of God in us will impel us to be concerned about their well-being.
As to the lost sinner, Christian love leads us to pray for him to come to the full knowledge of the Gospel of the Lord Jesus, and to take or arrange for the Gospel to be taken to him.
Christian love is the reflected image of the love of God for us. Perseverance in loving is the proof that a person is born of God and knows God. If this isn't so, simply stating that one loves God accompanied by a lack of love for a brother is a lie (1 John 2:9-11). The reason is that love comes from God.
When we find a person who professes to be a believer and we perceive that he loves us and loves other believers, we may conclude that he is a born again son of God. On the other hand, a person who does not show love for us and other believers has never come to know the love of God, because God is love.
The love of God was manifested in us (1 John 4:9 - not "amongst us" or "toward us" as in some translations): because He sent His only begotten Son, in order that we might live through Him; Jesus Christ is life (John 14:6), and He lives in us (Gal.2:20). This life begins when we receive Him as our Lord and Saviour.
Fellowship in the sense of having something in common, to share in a partnership or a mutual relationship, is described as follows in the Scriptures:
WITH GOD - It consists in the knowledge of His will (Job 22:21-26; John 17:3); in being in accordance with His designs (Amos 3:3); in abiding in Christ (John 15:4-7); in being in the Spirit (Rom.8:9); in being loved by God (Rom.8:38,39); in enjoying the light of His countenance (Psalm 4:6); in walking in His light (1John 1:6; 2:6); in sharing His joy and fulness (1Jo.1:3,4; Ef.3:14-21).
OF THE SAINTS, BETWEEN EACH OTHER - in duties (Rom.12:5-8; 1Cor.12; 1Tes.5:12-22; Rom.10:24; Heb.13:16); in ordinances and worship (Psa.55:14, 119:63; Mat.18:20; Acts 2:46; Heb.10:25); in grace, love, joy, etc. (Mal.3:16; Rom.12:15; 2Cor.8:4); in mutual interests, spiritual and temporal (Rom.12:13; Heb.13:16); in mental disposition and judgement (1Cor.1:10); in suffering and in support of the weak (Rom.12:15, 15:1,2; Gal.6:1,2,10; 1Tes.5:11); in glory (Ap.4:10,11). To live in fellowship with God, Father and Son, means to walk in the light of the Word of God (1John 1:7). It is not so much to walk "in accordance" with the light, the importance is on where we walk, not how. We must come to the presence of God and allow His Word to shine over our path. It is possible to walk in the darkness of sin, and still this that we are all right because we are fulfilling our obligations and "religious" commandments as we understand them.
Sin interrupts the fellowship of the believer with the Father and Son: the believer doesn't lose his salvation, but his fellowship is only re-established when the sin is washed away. It is necessary to allow the light of the Word of God to reveal our sin; repentance and confession to God will restore fellowship.
Nobody can have fellowship with the people of God without first having fellowship with God, in Christ, and to achieve this it is necessary to be walking in the light with God. On the other hand, if we walk in the light, we have fellowship with one another: this means that we meet with one another and participate with one another in that which is of Christ. We speak together about the Lord Jesus Christ and His Word. This is the type of fellowship which arises when we hear and believe in the witness of the Bible, and it is impossible to have this fellowship with unbelievers. Our joy becomes complete when we have fellowship with each other, as a consequence of having fellowship with the Father and His Son Jesus Christ.
The third letter of John contrasts two opposite attitudes concerning "strangers", these being believers coming from another locality: hospitality and presumption. The person to whom the letter was addressed, Gaius, practised love to the brethren faithfully, even those coming from outside his church, receiving them and providing for their needs, having fellowship with them. In contrast, a certain Diotrephes loved to have the pre-eminence over the local church, required everything to be done as he wanted and wouldn't admit anything not to his liking.
Diotrephes was always right in his own opinion, he didn't bear opposition, nor did he know meekness or modesty. His presumption was such that he wouldn't even receive the apostle John, prating against him with malicious words, refused to receive those who came from outside, forbade those who wished to and put them out of church. John puts him among those who have never seen God, for he practised evil by not extending communion to those from outside his own church.
Love and fellowship ought to be the main characteristics of the meetings of the church, always prevailing over some forms of legalism introduced in them and remaining there as if they were divine commandments. No doubt the meeting which becomes most restricted because of this interference is that in which the Lord's Supper is celebrated.
This meeting ought to be open to the full leadership of the Holy Spirit over the believers present there, obedient only to the instructions given in His Word (1Cor.14:26-40, etc.). Each participant must examine himself before participating in the elements (1Cor.11:28). We see, however, various restrictions being imposed by those who are overseers of the assembly, acting like little Diotrephes in the locality. They shall give account to God of their procedure.
Although all the disciples of Christ are invited to take part in the Supper, usually other people, who have not yet confessed Him as Lord, nor have been baptised in His name, are also present as visitors. They do not have the privilege of participating in the worship or the elements, but the death of the Lord is in this way announced to them, being an integral part of the message of the Gospel. Though they are not in fellowship, we must extend to them our Christian love so that they may come to the full knowledge of the Truth and be converted.