Joshua 23:6 “Be very strong; be careful to obey all that is written in the Book of the Law of Moses, without turning aside to the right or to the left.”

Are Christians weak or are they strong? We can look at great Biblical leaders of the past–men like Noah, Abraham, Moses, David, the prophets, Peter, and Paul. We can see how they took their stand on the truth, and lived and sometimes even died there, and it looks to us as though they are strong. Maybe you have had some great Christian role model in your life. You have seen how he or she resisted temptation, weathered personal tragedy or persecution with a robust, unwavering faith, and you aspired to stand strong like they do. Maybe Christians are strong.

Oh, but “pride goeth before a fall.” Noah got drunk, Abraham slept with a servant girl, Moses and David committed murder, Peter denied his Lord, and Paul admitted his unending struggle with sin. The idea that the church is more a hospital for wounded sinners than a gymnasium for burly saints goes back at least as far as Luther. Given enough time, even the Christians you respect the most will let you down. Their feet are made of clay, not iron. Maybe Christians are weak.

So which is it–are they weak or are they strong? True to reality, it’s not a simple “either/or.” The best answer is “both.” Like Paul says, “Therefore I will boast all the more gladly about my weaknesses, so that Christ’s power may rest on me. That is why, for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.”

Huh? In these words of farewell to his people Joshua urges us, “Be very strong.” But what’s the point of telling people to do that if they always are? Because we often struggle, we need this encouragement. But we also need to know what real strength looks like and where real strength comes from. That’s where Joshua’s words direct us.

When Joshua says “Obey everything written in the law of Moses,” he is commanding more than obedience to a list of rules. “The Law of Moses” was the technical term for the first five books of the Bible. While it is true they contained many commands, they were also filled with history and promises and examples. A fuller translation of “obey” would include the words “keep” and “do.” There were certainly things to “do” here. None of the commandments was optional.

But just as important as the laws were the promises and examples for them to keep and preserve in their hearts. These five books of Moses contained the first promises of a Savior–the One who would crush Satan’s head, make Israel a blessing to all nations, a Ruler who would come from Judah, a Prophet who knew God more intimately than Moses, the Sacrifice that all the sacrifices at the Tabernacle were pointing to. Joshua and his people knew this Savior as a promise. We know him as Jesus, and we know the full story of his love and the full forgiveness he died to give us. If you are standing on a foundation of God’s grace and love like that, you can be strong for the struggle.

These five books of Moses contained examples of God’s great power to deliver his people like Noah’s Ark, Joseph’s rise to power in Egypt, the 10 plagues and the Passover, and the crossing of the Red Sea. They were filled with providential promises like, “There is no one like the God of Jeshurun who rides on the heavens to help you and on the clouds in his majesty. The eternal God is your refuge, and underneath are the everlasting arms” (Deut. 33:26-27). An old hymn reminds us that we are “Standing on the Promises,” and that is just what Joshua was urging his people to do so that they would stay on the right path.

When God’s weak, fallible people hold on to the promises, and depend on his power, they don’t just find help. They are very strong.