Three Days and Three nights

The "Three days and three nights" issue stems from a failure to understand Jewish holidays.  The Bible says Jesus was crucified on the day before the Sabbath.  If you don't know anything at all about Jewish holidays (like the Passover) you have to say the Crucifixion was on Friday.

But if you have a Jewish holiday in the mix, you can add additional Sabbaths to the week.  Jesus was crucified on Thursday.  Friday and Saturday were both Sabbath days that week.  For example, Leviticus 23:26-32 speaks of Yom Kippur, the Day of Atonement, and verse 32 fixes a Sabbath day on the 9th day of the month... regardless of what day of the week that is.

Leviticus 23:32
It shall be to you a Sabbath of solemn rest, and you shall afflict yourselves. On the ninth day of the month beginning at evening, from evening to evening shall you keep your Sabbath.”

Jesus was crucified, then, on the day before the Sabbath, but in this case, it was not the weekly Sabbath, but rather the High Sabbath for the Passover.

So Jesus was dead on...

Thursday NIGHT............................  Friday DAY,
Friday NIGHT...............................Saturday DAY,
Saturday NIGHT...and a portion of Sunday DAY.

Why do I say just a portion of Sunday?  Because He was raised ON the third day, not AFTER the third day.

Matthew 17:22-23a
As they were gathering in Galilee, Jesus said to them, “The Son of Man is about to be delivered into the hands of men, and they will kill him, and he will be raised on the third day.”

Why do we have Good Friday celebration, then?  The same way we remember Memorial day on a Monday, or we observe a holiday that falls on a Saturday by taking Friday off.  It's more convenient for a civilized society.

But very few educated Christians believe that Jesus was crucified on a Friday.

There are two common errors people make with this:  One, they try to force it to fit the "Good Friday - Resurrection Sunday" narrative.  When they do that, they are forced to make the argument that "counting is cultural," and "any part of a day or night counted as a whole day or night."  Even if that's the case, we do not see the third night, even partially.  We see Friday Day, Friday Night, Saturday Day, Saturday Night, Sunday Day.... but even with the most generous counting method possible, we only see three days and two nights between Friday and Sunday.

The other mistake people commonly make is to insist that "Three days and three nights means three full days and three full nights.  72 hours exactly!"  But I have already answered this objection above:  Jesus did not complete the third day in the tomb.  The Scripture says he rose "on the third day," not after it.

That is why I hold to a Thursday evening crucifixion.  Jesus died on the day of preparation, as Matthew 27:62 indicates.

62 The next day, that is, after the day of Preparation, the chief priests and the Pharisees gathered before Pilate 63 and said, “Sir, we remember how that impostor said, while he was still alive, ‘After three days I will rise.’ 

That is, they do this the day after the crucifixion, which Matthew tells us is also the "next day," the one after the day of Preparation.

The Day of Preparation is the day when Jewish households would do extra work to prepare for the rest of the Sabbath.

Mark 15:42 agrees:
42 And when evening had come, since it was the day of Preparation, that is, the day before the Sabbath,

Also, John 19:14-16:
14 Now it was the day of Preparation of the Passover. It was about the sixth hour. He said to the Jews, “Behold your King!” 15 They cried out, “Away with him, away with him, crucify him!” Pilate said to them, “Shall I crucify your King?” The chief priests answered, “We have no king but Caesar.” 16 So he delivered him over to them to be crucified. 

But if Friday was the High Sabbath (probably of Unleavened Bread) and Saturday was the Weekly Sabbath, then the women, who were obviously eager to anoint the Body (they began their journey to the tomb before sunrise) would have had to wait two full days of Sabbath observance before they could defile themselves by touching a dead body.