In a sermon preached on 20th October , 1889 C H Spurgeon commented on the parable of the mustard seed:
It was one single seed, and that seed a very small one; so very, very small that the Jews were accustomed to say, “As small as mustard seed.”
Yes, the Gospel seems a very simple thing: Believe and live! Look to Jesus lying in the sinner’s stead! Look to Jesus crucified, even as Israel looked to the brazen serpent lifted up upon a pole. It is simplicity itself; in fact, the Gospel is so plain a matter that our superior people are weary of it and look out for something more difficult of comprehension.
Sowing seed is work too ordinary for the moderns; they demand new methods. But, beloved, we must not run after vain inventions; our one business is to sow the Word of God in the minds of children. It is yours and mine to teach everybody the simple truth that Jesus Christ came into the world to save sinners, and that whosoever believes in Him shall not perish, but have everlasting life. We know nothing else among adults or among children. This one seed, apparently so little, so insignificant, we continue to sow.
They sneeringly say, “What can be the moral result of preaching such a Gospel? Surely it would be better to discourse upon morals, social economics, and the sciences?”
Ah, friends! If you can do any good in those ways, we will not hinder you, but our belief is that a hundred times more can be done with the Gospel, for it is the power of God to salvation to everyone that believes. The Gospel is not the enemy of any good thing; say, rather, it is the force by which good things are to be carried out. Whatsoever things are pure and honest and of good repute are all nurtured by that spirit which is begotten by the simple Gospel of Christ. Yet conversions do not come by essays upon morals but by the teaching of salvation by Christ. The cleansing and raising of our race will not be effected by politics or science, but by the Word of the Lord, which lives and abides forever. To bring the greatest blessings upon our rising youth we must labour to implant in their minds faith in the Lord Jesus. Oh, for divine power in this work!