33 Another parable He spoke to them: “The kingdom of heaven is like leaven, which a woman took and hid in three measures of meal till it was all leavened.”
34 All these things Jesus spoke to the multitude in parables; and without a parable He did not speak to them,
35 that it might be fulfilled which was spoken by the prophet, saying: “I will open My mouth in parables; I will utter things kept secret from the foundation of the world.”
three measures (v.33) — a common baking measure — about a gallon and a half
It has been correctly pointed out that it is both important and interesting to interpret any expression or thought in Scripture by the presence thereof in other parts of Scripture, and especially by its first occurrence. Following that principle of investigation, we find that the first occasion upon which the three measures of meal are mentioned in Scripture is as far back as Genesis 18:6. There we have an account of the entertainment of Jehovah by Abraham. In one of the great Theophanies of the Old Testament Jehovah manifested Himself as an angel. Recognizing Him as supernatural, Abraham hastened to entertain Him. Sarah took three measure of meal and prepared it. Passing on through eh Bible I find the figure again in connection with the meal offering. For this there was fixed a minimum and maximum amount. Gideon brought an offering, and Hannah also, and on each occasion three measures of meal are spoken of. In the book of Ezekiel, in connection with the final and perfect offerings, seven times over in one brief instruction the amount of the meal offering is three measures of meal. In the Divine economy the meal offering followed the burnt offering. The burnt offering signifies the devotion of the life to God. The meal offering was the result of cultivation, manufacture, preparation, and, therefore, so far as man was concerned, always signified dedication of his work to God. Remember, too, the meal offering was an offering of hospitality; part was retained by the worshiper and part was at the disposal of the priest. In the meal offering, then, we have a symbol of the perfect communion established between the worshiper and God upon the basis of the worshiper’s service. From the simple rites of home life was taken that which was to be the perpetual symbol of dedication to God in service as the ground of perpetual communion with Him. — Morgan, pages 159-160
Leaven is in itself corrupt, and is always an agent of corruption. When Sarah prepared the meal for the angel, she mixed no leaven with it. Leaven was distinctly forbidden in the meal offering, and when Paul used the figure of the leaven, whether in reference to the Levitical code, the Jewish custom, or the Master’s use of it, it was always in the sense of evil. “your glorying is not good. Know ye not that a little leaven leaveneth the whole lump? Purge out the old leaven, that ye may be a new lump, even as ye are unleavened. For our passover also hath been sacrificed, even Christ: wherefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth (1 Corinthians 5:6-8). — Morgan, page 160
The first use of “leaven” in the New Testament, in the actual reading of the books rather than in the chronology of events, is in our text. Later on, as the King came to Caesarea Philippi, and approached the crisis when the period of His propaganda merged into that of His passion, He warned His disciples to “Beware of the leaven of the Pharisees and Sadducees.” Mark tell sus that He said, “Beware of the Leaven of the Pharisees, and the leaven of Herod;” while Luke reports Him as saying, “Beware ye of the leaven of the Pharisees, which is hypocrisy.”
Coming to the letter to the Corinthians, Paul uses the figure in connection with the toleration in the church of an incestuous person, and the lack of discipline which characterized that toleration. Yet again, in the Galatian epistle, in combating the influence of Judaizing teachers, Paul declared, “A little leaven leaveneth the whole lump.” These referenced exhaust the use of the figure in the New Testament. Thus in the Old and New alike, leaven is the symbol of that against which the men of faith are to guard. — Morgan page 161
The quote in v.35 is from Psalm 78:2.
Again, the commentaries apply this parable to the current age. I’ve already given my reasons why I don’t agree with this.
There will be sin in the kingdom. It will be judged (Isaiah 65:20) as it was with Ananias and Sapphira (Acts 5), but it will be there.
The kingdom will start with all believers, of course, all unbelievers having died off at Armageddon. However, these believers will have children who can’t inherit salvation — they must believe for themselves. As is the case now, the majority of people don’t believe. Thus by the end of the kingdom, Satan is able to amass an army against God “whose number is as the sand of the sea” (Revelation 20:7-8). That’s how “the whole was leavened”, as the parable says.
The parable features a woman introducing the leaven since she is the one who bears the children who will leaven the kingdom.