Compare Luke 13:18-21
The parable of the mustard seed seems to suggest that the Church, though initially dismissed as tiny, insignificant, and irrelevant, will grow to a surprisingly large size. And this, of course, seems already to have happened — not just anciently but in the current dispensation. (Founded with a membership of six in 1830, the Church of Jesus Christ of Latter-day Saints now numbers well over sixteen million members.)
But, of course, large and small are relative. Some remain unimpressed, pointing out that many nominal members of the Church are inactive and that we haven’t yet managed to grow to hundreds of millions if not billions. (Of course, at a comparable stage of its history — around AD 215 — the early Christian church was still relatively insignificant. It hadn’t yet become “Christendom.”)
So the parable of the leaven is also worth a quick look. It seems to allow that the Church will remain relatively small, but to predict that it will “leaven” the entire world “loaf,” meaning that it will spread around the globe.
This is consistent with what we actually see today, and with what is predicted in 1 Nephi 14:9-12:
And it came to pass that he said unto me: Look, and behold that great and abominable church, which is the mother of abominations, whose founder is the devil.
And he said unto me: Behold there are save two churches only; the one is the church of the Lamb of God, and the other is the church of the devil; wherefore, whoso belongeth not to the church of the Lamb of God belongeth to that great church, which is the mother of abominations; and she is the whore of all the earth.
And it came to pass that I looked and beheld the whore of all the earth, and she sat upon many waters; and she had dominion over all the earth, among all nations, kindreds, tongues, and people.
And it came to pass that I beheld the church of the Lamb of God, and its numbers were few, because of the wickedness and abominations of the whore who sat upon many waters; nevertheless, I beheld that the church of the Lamb, who were the saints of God, were also upon all the face of the earth; and their dominions upon the face of the earth were small, because of the wickedness of the great whore whom I saw.