Did I incorrectly teach the parable of the yeast?

Question:

Good day, brother Jeffrey.

I led a study during our Mid-Week Service about the Parable of the Yeast. I made a disclaimer in my lesson that even though the majority of the usage of the word "yeast" in the Bible carries a negative connotation but the way Jesus used it in Matthew 13:33 leaned on the positive side (pointing out that it is a follow-up idea after the parable of the mustard seed).

The lesson I presented was very simple. I pointed out that just like the yeast, even though it's small, almost invincible, yet it changes or transforms everything it touches. The kingdom of God (church) is the same. It might look small in the eyes of the world, but its influence is unstoppable.

The challenge I left to the listeners is to make a personal change (we are a new creation in Christ, so there must be a change inside out). Make an impact in our community (being a light and salt whenever we are) and keep the kingdom growing (the great commission).

Now, in our Facebook livestream, a brother made a comment that I should "take into consideration that leaven is used in a bad or negative sense because the intention of the yeast is hidden in the flour. Since it is mixed with only a little leaven, it affects all. The whole context of chapter 13 is Jesus telling those who are followers to beware. I'm just sharing my understanding, but there is no evil with the yeast."

I also made a response when I read his comment (since we recognize and greet those who are present in the livestream), repeating my disclaimer that Jesus presented the leaven or yeast in the positive sense. I explained that Jesus used the yeast to explain what the kingdom of God is like, just like the earlier parable (mustard seed).

Later that night, I received a message from that same brother in Christ. He sent me a document of his presentation to explain why he thinks otherwise. In it, he said, "In Matthew 13, Jesus is clearly connecting through a series of parables, the emphasis to beware to 'give no importance to his seedling or sowing' and to keep hold on, growing, the implanted 'pure seed' in our hearts, unmixed or ignored." He goes on to say,

"Take a look at the emphasis of Jesus in every parable. In the Parable of the Sower, Jesus said to take care that the pure word is not snatched or given little importance or application. Jesus emphasizes to them not to let it happen, to give no importance or ignore his pure seed word. All the seed scattered was pure, but it did not receive or grow to the three kinds of heart, except the good soil. Why these three kinds of hearts? Because of the influence of the world and other false teachings. But the one who hears, receives, takes it to heart, and lives, will be blessed. In the Parable of the Wheat and Tares (Matthew 13:24), Jesus is saying to take care of other seeds, not the pure teaching of Jesus, due to false teachings by false teachers and other influences today. He differentiates between the good seed sown by the sower and the enemies who sowed evil seed. But Jesus said, "Let’s wait till the Judgment, or let them grow together." The good seed-crop will be harvested, but the evil seed, “tares or other plants," let it remain and be burned. It seems Satan is trying to confuse, to sow bad seed in each person's heart, using the evil or bad seed. Now, to the Parable of the Leaven, the question is whether the leaven or yeast was used or symbolized good and purity in the kingdom? No! Yeast or leaven does not embody or symbolize purity, but rather mixes the pure flour or grains. and has the power to destroy or exert a negative influence. Besides, the parable does not suggest that the woman is making bread; rather, the woman was not careful or thoughtful in hiding the huge amount of flour, which might be considered negligent or unintentional, when combining it with the yeast or leaven. In this parable, you might understand that the use of yeast or leaven is “destroying’ or damaging the whole.

It made me worried since I might have probably taught the wrong things, but looking back at the lesson I presented, I don't see the error. However, if I did, I am willing to stand before the congregation to apologize for the incorrect teaching I provided during our Mid-Week service.