Really, the one who is going to make himself small like this little child is the one who is the fullest grown in the universal state.
Whosoever therefore shall humble himself as this little child, the same is greatest in the kingdom of heaven.
Interesting and Hidden Aspects:
This line is typical of Christ's teaching that the the spiritual world reverses the physical world. Here, the play on words here is lost almost entirely in translation. In this case, if you lessen yourself on earth, you become great in heaven. If you become a child on earth, then you become an adult in heaven.
The Greek word translated as "therefore" either emphasizes the truth of something ("certainly", "really") or it simply continues an existing narrative.
"Humble" is from a verb that means "to lower", "to reduce", "to lessen", "to disparage", "to minimize," and "to humble."
The word used for "child" means specifically a little child.
"Greatest" is from an adjective which is the comparative adjective form of megas (great), which means "big", "full grown", "great", "might" and "strong."
The phrase "kingdom of heaven" is one of those used frequently by Jesus. It is discussed in detail in this article.
The word translated as "heaven" means sky, the climate, and the universe. It also meant the home of the gods in a physical sense: the sun, moon, and planets were named for the gods.
A play on the word for "make small" against the idea of being "the largest."
ὡς "As" is from hos, an adverb which means to "thus", "as", "how", "when", "where", "like", "just as", "so far as", "as much as can be", "that", "in order that", "nearly (with numbers)," and "know that."