We must not ignore the Old Testament and think it unimportant. Moses and Elijah, and the rest of the Old Testament, are the background for Jesus. If we want to understand Jesus better, we need to know the Old Testament. It is there we read of creation and sin, of sacrifice, of covenant promises, of God’s presence, and so much more.
The Old Testament is rich and full of useful things for Christians to think about. We see how God relates to his people, his faithfulness to the promises, and instructions about how to live. All of that is true. Yet there is a real danger that we don’t see the Old Testament in the right light. The transfiguration of Jesus helps us to avoid a few fundamental mistakes that it is easy to make.
In the transfiguration, Jesus was transformed with his face and clothes glowing. And while he was in this transformed state, Moses and Elijah appeared beside him.
(As an aside, this raises all kinds of issues for us. How did the disciples know they were Moses and Elijah? Were there nametags or subtitles or something? Were they really there or some kind of vision? This is one of those passages we wish we had more detail in, but we are told what we need to know.)
Why Moses and Elijah? Well, together they symbolise the Old Testament. Jesus often referred to the Old Testament as the Law and the Prophets (as in Matt 5:17, 7:12). Moses wrote the Law, the first five books of the Old Testament. Elijah didn’t write any books, but he is the greatest of the prophets in the Former Prophets. So these two men represent the Old Testament.