Now there appears with the Lord on the mountain Elias [Elijah] and Moses, representing the prophets and the law, and in the transfiguration the law and the prophets are seen to be subservient to Christ, and serving him, and pointing forward to him, the risen glorified Christ. We cannot really say that this was a vision, for certainly Christ was literally in front of them, though changed in appearance.
It would communicate to them that his sufferings were voluntary. He didn’t have to do this. He was God! He had all power. He could deliver himself easily. This would be reinforced in their minds and therefore everything he was about to submit to was voluntary, to save souls. Then they would see (and it would occur to them later on) what dignity and majesty was being invested in the cross of Calvary. They had only seen him in all his holiness, yes, and his perfection of character and his beauty and his power to work miracles and his wonderful speech, they had seen those things, but now they would see radiant divinity and perfection and eternity and they would think later on – what qualities, what infinite Godhead was invested in the work of Calvary for us to take away our sin. What God has invested there.
There's an idea today among some evangelical preachers that the secrets of the kingdom are the ugly side of Jewish history. The idea is that the Old Testament is all about how God was with Israel, the great things. But there is hidden there an ugly side: their disobedience and idolatry, and the meaning, say, of the parables, which is about the secrets of the kingdom, is to bring out the ugly side. So it infuriates the Jews when they hear it, and they are against it. But that's a very dismal and negative idea of what the secrets of the kingdom are. and it takes away the parables as figures and illustrations of grace and salvation. Besides, the ugly side of Old Testament history is no secret; the Old Testament makes it very plain. It speaks of the blessings and the privileges, and it speaks endlessly of the periods of disobedience and failure and judgment and captivity. No, the secrets of the kingdom, the Old Testament, are the symbolic typical foreshadowed meanings. The Jews stayed with the literal. They said, ‘God is so pleased with us as a nation that he has given us this ancient system of worship: the sacrifices and all the ablutions’, and they never looked the meaning of those things. They never said, ‘This symbolises or depicts Messiah and the great sacrifice that would come. These sacrifices of animals cannot take away sin. They symbolise our dependence upon the great sacrifice that will come. All these washings cannot take away soon; they symbolise the purity and the unreachability of God, and the need of grace and free forgiveness from him.’ Those are the secrets of the kingdom: the meaning. So for instance, when Moses struck the rock for the first time at Horeb, and the water flowed – a provision for the people. The meaning was that by something being struck – stricken, pain, and hurt – grace would flow from that riven rock. That represents Christ, and Paul says so in 1 Corinthians 10. He lists many of the features of the Old Testament and shows how they point of Christ. It's Christ who was smitten, and from him comes – because he atoned for sin – the grace of forgiveness. Toplady has it in his hymn: ‘Rock of ages cleft for me, let me hide myself in thee.’ Of course the faithful and the earnest Jew, of old times got it. They could see the secret, even then. But it didn't come into full view to be proclaimed to all until the New Testament, and the task of the apostles was to bring these mysteries and secrets into the open light of day.