[Moses] said to them, 'Take to heart all the words by which I am warning you today, that you may command them to your children, that they may be careful to do all the words of this law. For it is no empty word to you, but your very life, and by this word you shall live long in the land that you are going over the Jordan to possess.' (Deut. 32:46–47).God promised Israel long life in the land if they would keep the covenant between them and God—if they kept the law and obeyed God's word. The Word was their life. That sounds so...Pauline. "When Christ who is your life appears..." (Col. 3:4). But back to the story. It's no secret that Israel failed at being "careful to do all the words of this law." They couldn't even if they tried. God's promise to them, however, was that they would live long in the land He was giving them. Keep that scenario in mind. Israel had this promise—and the Word—but they failed, repeatedly. Just like we do.
Then Christ came. And he did keep all the words of the law. Some even say he was the embodiment of the law—he was the Word of God made flesh. So it's easy to see how Paul could say that Christ is our life. It wasn't a novel concept—Moses said the same thing way back in the desert. But here's the great news: despite our failure, Christ obtained the promise for us, and he gave his righteousness to us. Therefore, we have an even greater promise. Where Israel (a type of the church) was promised long life in the land through their obedience, we (the church) are promised eternal life in the New Jerusalem through Christ's obedience. What a promise! What a salvation! What a possession!
Moses was right. The Word of God was no "empty word," as if it were powerless, but our very life. For without The Word, we have no life. And as Israel went over to possess the land for a long time, we go over to possess a greater land for eternity. Both by God's word, our life.