So we see that they were unable to enter because of unbelief. (Hebrews 3:19)
Even though the people of Israel saw the waters of the Red Sea divide and they walked over on dry ground, the moment they got thirsty, their hearts were hard against God and they did not trust him to take care of them. They cried out against him and said that life in Egypt was better.
That is what this verse is written to prevent. O how many professing Christians make a start with God. They hear that their sins can be forgiven and that they can escape hell and go to heaven. And they say: “What have I got to lose? I'll believe.”
But then in a week or a month or a year or ten years, the test comes — a season of no water in the wilderness. A weariness with manna, and subtly a growing craving for the fleeting pleasures of Egypt, as Numbers 11:5–6 says, “We remember the fish which we used to eat free in Egypt, the cucumbers and the melons and the leeks and the onions and the garlic, but now our appetite is gone. There is nothing at all to look at except this manna.”
This is a terrifying condition to be in — to find yourself no longer interested in Christ and his Word and prayer and worship and missions and living for the glory of God. And to find all fleeting pleasures of this world more attractive than the things of the Spirit.
If that is your situation, I plead with you to listen to the Holy Spirit speaking in this text. Give heed to the Word of God. Do not harden your heart. Wake up to the deceitfulness of sin. Consider Jesus, the apostle and high priest of our great confession, and hold fast to your confidence and hope in him.
And if you have never even made a start with God, then put your hope in him. Turn from sin and from self-reliance and put your confidence in a great Savior. These things are written that you might believe and endure, and have life.