And when the sixth hour had come, there was darkness over the whole land until the ninth hour.And at the ninth hour Jesus cried with a loud voice, “Eloi, Eloi, lema sabachthani?” which means, “My God, my God, why have you forsaken me?” And some of the bystanders hearing it said, “Behold, he is calling Elijah.” And someone ran and filled a sponge with sour wine, put it on a reed and gave it to him to drink, saying, “Wait, let us see whether Elijah will come to take him down.” And Jesus uttered a loud cry and breathed his last. And the curtain of the temple was torn in two, from top to bottom. And when the centurion, who stood facing him, saw that in this way hebreathed his last, he said, “Truly this man was the Sonof God!” (Mark 15:33-39, ESV)
When God created the world, He said, "Let there be light" and the light appeared. He is light and in Him there is no darkness at all (1 John 1:5). Yet, there was a day when God the Son hung upon a cross in darkness. The Light of the World was surrounded by darkness. The darkness was not His own, instead it was our darkness--our sins. Yet, because He bore our darkness we can now have the light of life in Him:
Again Jesus spoke to them, saying, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life" (John 8:12).
For just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth" - Matthew 12:40 (ESV)
In this brief post, "Good Friday...or was it Wednesday or Thursday?" Walter C. Kaiser Jr. explains what the biblical writers meant by three days and three nights.