Yeast (there are over 1,500 species) gets everywhere! It is a fungus which grows wherever it can find sugars. Yeast is the naturally occurring 'bloom' on grapes and other fruit which enables fermentation of the sugary contents into alcohol and carbon dioxide. We use yeast's ability to produce gas in a flour-mix, enabling it to 'rise' when we make bread. Yeast is also very hardy; when conditions are not right for growth, spores form which are able to resist the harshest conditions and can live for ever without water. As tiny light particles, yeast can be blown by the lightest wind and carried by animals and birds and human transport. However, immediately water and sugars are available the spore germinates and very quickly multiplies.
Usually, in the Bible, yeast is a picture of impurity and sinfulness - because it gets everywhere (1 Corinthians 5:6-8). It is impossible to eradicate and is highly infectious. But in this parable, Jesus used yeast as a picture of the kingdom of God, for the same reasons - it would get everywhere, would be impossible to destroy and wherever hearts are receptive, the grace of God will take root and grow fruitfully. Whenever the yeast of the gospel is mixed with faith, the kingdom of God grows: Hebrews 4:2 says, "For we also have had the good news proclaimed to us, just as they did; but the message they heard was of no value to them, because they did not share the faith of those who obeyed."
Like birds and animals (and aircraft!) carrying yeast spores, the workers in God's kingdom are often unaware of the potency of the gospel of Jesus they carry with them. Wherever they go, the seeds of the kingdom travel. That happened during times of persecution when believers had to flee their homes and countries (Acts 11:19-21). Yet, for the gospel to germinate, it needs to be mixed into hearts that will believe it. Scattering gospel seed is not just the work of full-time clergy and missionaries; it is the work of every believer. Then their lives will become fruitful in growing God's kingdom.
Such followers of Jesus Christ are found in all sorts of routine employment, travelling on business or meeting strangers in the course of their work. They are conscious of their responsibility to spread the truth of the gospel and to invest time with those who are starting to want to believe. So be much encouraged ... God's kingdom is unstoppable (Mark 4:30-32), the gospel is still the power of God for the salvation of all who believe and you have an essential part to play in His kingdom ... be aware of it, commit yourself to kingdom growth and work hard at it wherever you find the opportunity!
© Dr Paul Adams