Answer
Figurative language is used throughout the Bible to symbolize spiritual truths. The concept of growing fat is one such example. However, in Scripture, “to grow fat” takes on a different association than it does today.
Let’s examine the expression in Deuteronomy 31:20 for context. At the time, the nation of Israel was poised to enter the Promised Land. Moses was preparing to pass the leadership torch to Joshua. It was important for God’s freshly appointed leader to know what lay ahead—the people would abandon the Lord for foreign gods: “For when I have brought them into the land flowing with milk and honey, which I swore to give to their fathers, and they have eaten and are full and grown fat, they will turn to other gods and serve them, and despise me and break my covenant” (ESV).
Grow fat means “to prosper or thrive.” Through Moses, God warned Joshua that, as soon as the Israelites had eaten their fill and begun to grow rich and thrive in the Promised Land, the nation would turn away from the One True God to serve false gods. And because Israel would abandon the Lord, God would allow tragedy into their lives to bring them back to a place of repentance, dependence, and restored covenant relationship (Deuteronomy 31:21).
We can learn much from the Israelites as they grow fat. God told Moses to write the warning in a song for Israel to memorize so it would not be easily forgotten (Deuteronomy 31:19–21). First and foremost, we must remember, in times of plenty, when we are enjoying God’s blessings of prosperity and abundance, not to grow complacent and self-sufficient. We must never forget where our blessings come from (Deuteronomy 8:17–18). God is the source of every good thing (James 1:17). He expects and deserves our loyal love and faithfulness at all times (Deuteronomy 7:6; 10:12; Exodus 34:14). Unfortunately, just like Israel, we all have the fatal inclination to “grow fat” and forget the Lord whenever life is good and we are thriving (Psalm 14:2–3; Isaiah 53:6).
God knows how rebellious and stubborn we are (Deuteronomy 31:27). This fact is proved in history again and again as Israel “grew fat and kicked; filled with food, they became heavy and sleek. They abandoned the God who made them and rejected the Rock their Savior” (Deuteronomy 32:15). It happened in Nehemiah’s day when the Israelites delighted in the Lord’s goodness rather than in the Lord Himself (Nehemiah 9:25–26). Jeremiah observed that Israel had “become fat and sleek” and “excelled in evil matters” (Jeremiah 5:28, HCSB). Through Hosea, God charged, “When I fed you, you were full. When you were full, you became arrogant. That is why you forgot me” (Hosea 13:6, GW).
God’s people of every generation have tended to be like the prodigal son who sought his father’s wealth but not his father’s will (Luke 15:11–24). Great success and fortune can quickly send us into a period of backsliding. Like the church in Laodicea, we become proud and apathetic. We think we are rich and prosperous, but in God’s eyes we are “wretched, pitiful, poor, blind and naked” (Revelation 3:14–22).
We can learn from the Israelites when they grew fat by guarding our hearts and our attitudes when we experience times of blessing. We would do well to keep this humble prayer of Agur constantly on our lips: “Give me neither poverty nor riches! Give me just enough to satisfy my needs. For if I grow rich, I may deny you and say, ‘Who is the Lord?’ And if I am too poor, I may steal and thus insult God’s holy name” (Proverbs 30:8–9, NLT).
Like the apostle Paul, we can learn to be content with whatever portion God provides—“with a full stomach or empty, with plenty or little”—by depending wholly on the power of Christ to give us strength (Philippians 4:11–13). Paul instructed Timothy to “teach those who are rich in this world not to be proud and not to trust in their money, which is so unreliable. Their trust should be in God, who richly gives us all we need for our enjoyment” (1 Timothy 6:17, NLT).
The lesson we must learn from Israel is to “grow fat”—to thrive and prosper—without ever forsaking the Lord. Until we learn this lesson, God, in His merciful love, will graciously lead us back to a place of faithfulness and humble obedience through the disciplines of hardship and suffering (Psalm 119:67; Hebrews 12:10–11; 12:6; 1 Peter 1:6–7).