J.C. Ryle on the Transfiguration account in Luke 9:
…this passage shows us that the Old Testament saints in glory take a deep interest in Christ’s atoning death. We are told that when Moses and Elijah appeared in glory with our Lord on the Mount of Transfiguration, they “talked with Him.” And what was the subject of their conversation? We are not obliged to make conjectures and guesses about this. Luke tells us, “they spoke of His decease, which He should accomplish at Jerusalem.” They knew the meaning of that death. They knew how much depended on it. Therefore they “talked” about it.
It is a grave mistake to suppose that holy men and women under the Old Testament knew nothing about the sacrifice which Christ was to offer up for the sin of the word. Their light, no doubt, was far less clear than ours. They saw things afar off and indistinctly, which we see, as it were, close at hand. But there is not the slightest proof that any Old Testament saint ever looked to any other satisfaction for sin, but that which God promised to make by sending Messiah. From Abel downwards the whole company of old believers appear to have been ever resting on a promised sacrifice, and a blood of almighty efficacy yet to be revealed. From the beginning of the world there has never been but one foundation of hope and peace for sinners–the death of an Almighty Mediator between God and man. That foundation is the center truth of all revealed religion. It was the subject of which Moses and Elijah were seen speaking when they appeared in glory. They spoke of the atoning death of Christ.
Let us take heed that this death of Christ is the ground of all our confidence. Nothing else will give us comfort in the hour of death and the day of judgment. Our own works are all defective and imperfect. Our sins are more in number than the hairs of our heads. (Psalm 40:12.) Christ dying for our sins, and rising again for our justification, must be our only plea, if we wish to be saved. Happy is that man who has learned to cease from his own works, and to glory in nothing but the cross of Christ! If saints in glory see in Christ’s death so much beauty, that they must needs talk of it, how much more ought sinners on earth!