Jesus said, “With what can we compare the kingdom of God, or what parable shall we use for it? It is like a grain of mustard seed, which, when sown on the ground, is the smallest of all the seeds on Earth, yet when it is sown it grows up and becomes larger than all the garden plants and puts out large branches, so that the birds of the air can make nests in its shade” (Mark 4:30-32).
Once again, let us not worry ourselves so much over church numbers. Is it concerning that there has been a mass exodus from the Church in recent decades? Of course it is. Do we want more people in the pews? Yes; this is a noble desire. Are these numbers a measurement of the Church’s success? No. Is the Church going to die off? No. For what does our Lord say about the kingdom of God?
It is like a mustard seed, which is minuscule. Is this not the Church? If Christ has inaugurated the kingdom of God in His incarnation, and the Church is, properly speaking, the Body of Christ (1 Corinthians 12:12-31; Ephesians 1:22-23), then this means He is talking about the Church in these parables. The Church may be “the smallest of all the seeds on Earth,” yet she will not die off; she will only continue to grow, for that is the Lord’s promise. People may be leaving the Church for all kinds of debaucheries, yet the Church will grow so large that her branches will overshadow these worldly kingdoms. We may not see it in our lifetime, and this enormous growth may not occur again here on Earth, but it will be fulfilled in the new Earth and the new heavens where John saw that incalculable multitude of the saints (Revelation 7:9). For, after all, even when a beloved saint dies, the Church’s numbers do not decrease but remain the same.
The Lutheran Column 