The "fellowship of the Spirit" (see 2 Cor. xiii. 13) is the common participation of the Holy Spirit of God in His gracious presence and working. Without this no one could have a real share in Christian benefits. The Spirit reveals to us the Son and the Father, and enables us to abide in the Son and in the Father. He brings us into communion with the mind of God as revealed in His word. He makes real to us the things of the Kingdom of God; and it is He who opens to us their worth and sweetness, especially the lovingkindness which breathes in them all. Through Him we are enabled to exercise Christian affections, desires, and services. It is He, in a word, through whom we are participant in the life of salvation; and in that life He associates together all who share His indwelling. The Apostle supposes that no Christian could ever contemplate without, shall we say, a pang of gratitude, the condescension, the gentleness, and the patience of this ministration. And as all Christians are recipient together of so immense a benefit, they might well feel it as a bond between them all. But more especially, as the Holy Spirit in this dispensation evinces a most Divine love and kindness--for what but love could be the spring of it?--so also the upshot of all His work is the revelation of God in love. For love is at the heart of all God's promises and benefits: they are never understood until we reach the love that is in them. And God is love. So the love of God is shed abroad in the hearts of believers through the Holy Spirit given to them. Hence this is the leading view of that which the Spirit comes to do: He comes to make us members of a system in which love rules; and He inspires all loving affections and dispositions proper to make us congruous members of so high and good a world.
Therefore, in the fourth place, it is to be supposed that "tender mercies and compassions" in human breasts are abundant where the fellowship of the Spirit is. How abundant they _might_ be: surely also in some measure they must be present; they must abound, amid all human infirmities and mistakes. All kinds of gentle, friendly, faithful, wise and patient dispositions might be expected. They are the fruits of the country in which Christians have come to dwell.
To all these the Apostle appeals. Perhaps a pathos is audible in the form of his appeal. "If there be any." Alas! is there then any? Is there some at least, if not much? For if all these had been duly present to the faith and in the life of the Church, they would have spoken their lesson for themselves, and had not needed Paul to speak for them.
The form of appeal "Fulfil ye my joy" brings up one more motive--the earnest desires of one who loved them wisely and well, and whom they, whatever their shortcomings, loved in turn. It is worth observing that the motive power here does not lie merely in the consideration "Would you not like to give me pleasure?" The Philippians knew how Paul had at heart their true welfare and their true dignity. That which, if it came to pass, would so gladden him, must be something great and good for them. If their own judgment of things was cold, might it not take fire from the contagion of his? The loving solicitude of a keener-sighted and a more single-hearted Christian, the solicitude which makes his heart throb and his voice tremble as he speaks, has often startled slumbering brethren into a consciousness of their own insensibility, and awakened them to worthier outlooks.
In regard to all these considerations, the main point is to catch sight of the moral and spiritual scenery as the Apostle saw it. Otherwise the words may leave us as dull as they found us. For him there had come into view a wonderful world of love. Love had come forth preparing at great cost and with great pains a new destiny for men. Love had brought in Paul and the other believers, one by one, into this higher region. And it proved to be a region in which love was the ground on which they stood, and love the heaven over their heads, and love the air they breathed. And here love was coming to be their own new nature, love responsive to the love of Father, Son, and Spirit, and love going out from those who had been so blessed to bless and gladden others. This was the true, the eternal goodness, the true, the eternal blessedness; and it was theirs. This was what faith embraced in Him "who loved me and gave Himself for me." This was what faith claimed right to be and do. If this was not so, Christianity was reduced to nothing. If a man have not love, he is nothing (1 Cor. xiii.). "Is there any truth at all in this glorious faith of ours? Do you believe it at all? Have you felt it at all? Fulfil then my joy." Unity of mind and of heart is the thing inculcated. Under the influence of the great objects of faith and of the motive forces of Christianity this was to be expected. Their ways of thinking and their ways of feeling, however different, should be so moulded in Christ as to reach full mutual understanding and full mutual affection. Nor should they rest contented when either of these failed: for that would be contentment with defeat; but Christ's followers are to aim at victory.