"Many people have been confused concerning the day of the death of Jesus. We know it was the day before the Sabbath, because the Jews wanted to get Him off the cross before the Sabbath. So traditionally people have believed Jesus died on Friday afternoon. But He had said He would be dead for three days and three nights, and we know He rose on Sunday morning, so that would only be two nights. Several explanations have been offered, but this passage here gives us a possible clue.
John tells us "that Sabbath was a high day." The day after Passover was the beginning of the Feast of Unleavened Bread. The first day of the Feast of Unleavened Bread was always considered a high Sabbath, no matter what day of the week it fell on. It was a special Sabbath day.
So I believe that Jesus was actually crucified on a Thursday, on the Day off Passover, with the next day, Friday, being the High Sabbath, the following day being the normal Saturday Sabbath, and the third day being Easter Sunday, the day He rose from the dead. This makes three days and nights. It also explains why His followers couldn't come to the tomb to anoint His body until three days later, as they couldn't do that on either Sabbath. We still celebrate the traditional Good Friday, but technically I believe it should be Good Thursday. "
Pastor Chuck Smith, Calvary Chapel Costa Mesa
an excerpt from The Word for Today Bible