Growing up in a Christian environment and religion, I was told that the "leaven of the Pharisees" is tantamount to "going under the law", with the following scripture being used as the proof text: “And Yeshua said to them, 'watch out and beware of the leaven of the Pharisees and Sadducees''" (Matthew 16:6). Paul, for his part, warns the believers that if they submit to the law of circumcision the Messiah will be of no benefit to them (see Galatians 5:2-3). He then adds to it by saying, “a little leaven will leaven the whole lump” (ref. Galatians 5:9). Thus, as a new believer, unaware of the above scriptures' context, I was left with the impression that Elohim has eliminated the “Old Testament” that is, the “Law”. Moreover, these interpretations had the potential of breeding an anti-Semitic attitude toward Judaism and the Jews.
But if we go back to the beginning, that is to Genesis. we will notice that leavening really has nothing to do with the 'Law'. The real 'leaven' actually came as a result of believing and acting upon (eating) the fruit of Satan’s words. Adam and Eve were leavened with the agent of sin and rebellion and every evil thing, and that included the “good” of the Tree of Knowledge. This leaven always results in puffing up the pride and righteousness of one's self-life. Because of what took place in the Garden of Eden, all of humanity has been leavened with “Sin”.
As believers in the New Covenant, we are exhorted to, “clean out the old leaven, that you [we] may be a new lump, just as you [we] are in fact unleavened" (emphasis added). How did we become unleavened from sin? “For Messiah, our Passover also has been sacrificed. Let us, therefore, celebrate the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth” (1 Corinthians 5:7-8). How important is this for us to grasp by faith and act upon!
The Torah helps to understand this great mystery of our cleansing from all the leavening of sin. Notice that our forefathers had to leave Egypt immediately after the Lamb had been slain. With its blood on the doorposts, they left in a hurry before the new dough had a chance to leaven. “And they baked the dough which they had brought out of Egypt into cakes of unleavened bread. For it had not become leavened, since they were driven out of Egypt and could not delay, nor had they prepared any provisions for themselves” (Exodus 12:39 emphasis added). Why the immediacy and how does it pertain to us? Could it have to do with our being joined to Yeshua in His death, and as He was hurried to the grave, so must we be buried with Him without delay in our immersion?
Messiah’s blood has cleansed and continues to cleanse us, so that we as a new lump of new creation's unleavened dough may be leavened by the “Kingdom of Heaven.” The Israelites of old were told that "nothing leavened shall be seen among you, nor shall any leaven be seen among you in all your borders…" This is how thoroughly we are to be cleansed by the blood of the Messiah. Furthermore, “…And you shall tell your son on that day, saying, 'It is because of what YHVH did for me when I came out of Egypt'" (Exodus 13:7b-8). How much more should we be telling the next generation of how YHVH took us out of the bondage of sin and death (at Passover) demonstrating to them that we have been cleansed of the old leaven and are now leavened with the Spirit, that is His Kingdom! “And again He [Yeshua] said, 'to what shall I compare the kingdom of Elohim? It is like leaven, which a woman took and hid in three pecks of meal until it was all leavened" (Luke 13:20-21).
We are coming to Shavuot and the time of the waving of two loaves of leavened bread, as it is written: "You shall bring in from your dwelling places two loaves of bread for a wave offering, made of two-tenths of an ephah; they shall be of a fine flour, baked with leaven as first fruits to YHVH” (Leviticus 23:17). The grain for these loaves is taken from the new growth of wheat hence the leaven in them is not the leaven of sin but the leaven of heaven. The reason being is that Yeshua was the "first- beginning wave offering that now allows us to partake of the new growth of His Kingdom. (See Acts 2)