‘Now he who plants and he who waters are one. But each shall receive his own reward according to his own labour. For we are God's fellow-workers. You are God's prepared land, you are God's building.'
Paul continues his illustration and then changes it to a new illustration. He is dealing first with the illustration of agricultural work. Then he changes to the illustration of building. So Christians are first depicted as land prepared for the growth of crops (georgion - cultivated land). And men of God, if they are true men of God, labour on them, planting and watering. And they are all one in the work. Their aim is one, and their unity is one. ‘That they may be one as we are' (John 17:11). And each will benefit individually according to how they labour. They work together as one, but as each is responsible individually, so each will be rewarded individually. For only God can see the heart. But the stress is also on the fact that they are only labourers in a small part of the field. It is Christ Who is central to it all. They are not of great importance, He is all important.
‘We are fellow-workers of God.' ‘Of God' may mean ‘who belong to God', or ‘who act together as fellow-workers on God's behalf' or ‘as fellow-workers with God'. As the emphasis is on their service for Him one of the first two is almost certainly correct (note that ‘of God' is repeated three times, in the two final examples definitely signifying possession)). The point is that they work together under God's management to fulfil God's work. It is the prepared land and the building which are important, not the farmers and builders. But we may also see the point as being that both the fellow-workers and the cultivated land/building belong to God. They share the same level as being His possessions. It is both a glorious fact and a great leveller.
If we take it to mean ‘in partnership with God', which is least likely, we must remember that in that case He is the driving force, and they are very much junior assistants. They are sun-ergos, ‘workers together' with God, working under His direction, and it is He Who pays their wages depending on the quality of their work. The thanks are due to the Owner and Managing Director and not his workers (although of course we may politely thank them too).
Then he changes his illustration to that of building, because he now wants to stress the centrality of Christ. The church of Corinth (and all churches) are seen as something being built. Initially therefore the following verses apply to Paul and Apollos and all those who labour likemindedly. But clearly in the final analysis they apply to all who work for God.
‘You are God's cultivated land.' God's people are the cultivated, fruitful land. The workers are privileged to have been called to work on that land. They dig, and plough, and sow, and water. But it is God Who gives the increase. Without Him all their work would be in vain.
‘God's building.' The new illustration is necessary to bring Christ into the picture.