Jeremiah 7 (selected verses) and Galatians 5 (selected verses)
As was often the case in the life of Israel, God was not happy with them. They brought it upon themselves. Israel’s history went something like this: God would first save them and then establish or reestablish a covenant with them. In response, Israel would repent, and then, after the good times were rolling, Israel would commit spiritual adultery (i.e., run off after foreign lovers). Predictably, after her disobedience (and the subsequent punishment for said disobedience), Israel would routinely cry out to God, be mercifully heard by him, and the whole process would start all over again.
It is Israel’s response to idolatrous and adulterous false teaching that our texts deal with today. The Lord, through Jeremiah, tells his people that if they are going to be allowed to continue to live in peace, then they are going to have to reform their ways and their actions (v. 3).
Verses 5-7 serve as a warning against wrong behavior and an encouragement for right behavior.
If you really change your ways and your actions and deal with each other justly,  if you do not oppress the alien, the fatherless or the widow and do not shed innocent blood in this place, and if you do not follow other gods to your own harm,  then I will let you live in this place, in the land I gave your forefathers for ever and ever.
So why would God’s people act disobediently? Verse 8 gives us a clue: They were trusting in deceptive words that were worthless.
Again, God says to them in verse 23,
…Obey me, and I will be your God and you will be my people. Walk in all the ways I command you, that it may go well with you.
God wanted so much to bless them, but he wasn’t kidding about what would happen if they didn’t obey him. However, they must have thought he was, for we read these sobering words in verse 24,
But they did not listen or pay attention; instead, they followed the stubborn inclinations of their evil hearts. They went backward and not forward.
God’s people were stubbornly committed to their sin… and for that sin we discover God’s indictment regarding them. Verse 28 tells us that truth had perished…that it had vanished from their lips.
Because they were no longer trusting in God’s Word, but trusting in the deceptive words of false teachers instead, they were soon to experience the wrath of God.
There’s a similar story in the New Testament. The Apostle Paul was bewildered with the Galatian Church. They had heard and responded to the pure Word of God as Paul had preached it. But, like God’s people in an earlier generation, many of the Galatians began trusting in deceptive words. They were being enticed to mix the finished work of Christ with their own works as a means of salvation. Paul was dumbfounded at such a move. We read in verses 7 and 8…
You were running a good race. Who cut in on you and kept you from obeying the truth?  That kind of persuasion does not come from the one who calls you.
God, through Paul, was warning them (and us) that such deceptive words were (are) like a little yeast, which works through a whole batch of dough (v. 9). It infects it like a disease. In the Bible, yeast often symbolizes evil or a false teaching.
When people begin to listen to deceptive words rather than the Word of God, trouble is sure to follow. Satan, the father of deceptive words, is not stupid. He will show us the worm, but not the hook. He will never show us the consequences that must follow his deceptive words. Instead, his words will always appear quite enticing, beautiful, practical, and relevant.
That is why everything must be tested against God’s Word – the Word properly understood. Even the best of intentions can be marred by deception. The church must constantly be on her guard against such yeast that seeks to contaminate her whole body. Whether it is what is preached from the pulpit, what is taught in a Bible study, the administration of a committee, or what programs are being implemented for evangelism, service or mercy, the church must always make sure she is taking her cues from God’s Word.
This may seem like a no-brainer, but today’s texts reveal that the church has not always gotten this right. In fact, the history of the church shows us over and over again what a little yeast can do. Even a cursory glance at the contemporary church scene shows plenty of evidence of the very idolatry and adultery that Jeremiah and Paul warned against.
So stand firm against all deceptive words. Cling to God and his Word as the only sure light by which to deal with the world, the flesh and the devil. Only with and through God’s Word may we know the one true God and his Son, Jesus Christ, whom he sent. That alone is eternal life (John 17:3).
Grace and Truth,