Fruit is part of a new testament analogy the talks about the results of our labor in God's kingdom.
Most of my thoughts on Fruit derive from the parable of the fig tree in Luke 13, in which Jesus describes the state of the Jewish nation, but which also applies to us individually, and to ministries or churches that we participate in.
In the old testament, fruit is a symbol of God's blessing, and points to the harvest in a primarily agrarian society. So what do I mean by fruit?
Fruit is the harvest – therefore evangelism, the great commission, the winning of souls in which we are to participate.
Fruit is spiritual growth – therefore discipleship, engaging God on a continually deeper level, and growing to spiritual maturity, growing in ever deeper dependence on and trust in God.
That is it. In our ministry to others, that is what God cares about. What is really unbelievable, is that while God allows each of us to participate in this fruit, we are not responsible for it, He is. That is why the analogy of the fruit and the harvest is so powerful to me.
We are like farmers. We cultivate the soil, we continue to work to keep weeds and animals from destroying the plants, and we reap the harvest. God is what causes the fruit to grow. We are just farmers. If we do not work the field, the harvest is small, like picking wild berries.
We are not God who makes the fruit grow, nor are we biologists and geneticists who are changing the nature of fruit, we are simple farmers.
The principle behind fruit is multiplication. You plant 1 seed, and a whole plant grows that produces lots of fruit that has its own seeds. These in turn are planted and grow into many plants, that produce more fruit.