Beginning in the last half of the last century, however, there have been a number of fresh approaches to resolving those conflicts. While a blog post is not the place for a critical review of the literature, I shall still try to give an overview of the most recent views and information.
Begin with the one fact one on which all four Gospels agree: Jesus was crucified and died on a Friday, the "day of preparation" before the Jewish sabbath. There was great concern about recovering his body and placing him in a tomb before sundown on the day he died, because of the impending Sabbath when no burials (or anointing of bodies) could take place. And the Gospels also all agree that it was early in the morning "on the first day of the week", i.e., Sunday, when the women hastened to the tomb to be able to complete the proper burial procedures for Jesus, only to find the tomb empty and the body gone.
So we have basic agreement on the three-day sequence of crucifixion, death and entombment on a Friday, everyone resting on the Sabbath, and discovery of the resurrection early Sunday morning. Beyond that simplified chronology, however, the conflicts and difficulties begin -- starting with the Last Supper.
The four Gospels also agree that the final sequence of events began with the Last Supper, followed by Jesus taking the disciples outside, to the Garden of Gethsemane, for prayer and vigil; followed by Jesus' betrayal, arrest, and trials, first before the high priest, then the Sanhedrin, then the first examination by Pontius Pilate, then an interrogation by Herod, and ending with his sentencing by Pilate. The disagreements begin with the nature of the Last Supper -- was it a Passover meal, as Matthew, Mark and Luke all describe it, or was it a meal taken on the eve of the day before Passover, as the Gospel of John takes great pains to make clear?
Resolution of this question interacts with the actual date of the crucifixion, which also has to do with the fixing of Passover in the Hebrew calendar used in the first century. Chapter 12 of Exodus, in verses 1-11, specifies the preparations for and celebration of Passover, always in the first month of the Jewish year. This month, originally called Abib in the Old Testament, had become known as Nisan (from its name in the Babylonian calendar used during exile) by the end of the Old Testament period. Exodus 12:6 requires that the Passover lamb be sacrificed on the 14th day of the first month, to provide the meal (with unleavened bread) for the start of the week-long Passover festival. That meal would take place after sundown on the day of the sacrifice, which was the start of the first day of Passover proper, on Nisan 15. (Although there is some dispute, most scholars agree that in the calendar system used by the Sanhedrin in Jerusalem in the first century, the day began with the first appearance of the stars after sunset, and ended with sunset on the following day.)
It is this unique feature of calculating the days in the Hebrew calendar, and matching those days to our own Julian/Gregorian dates, which causes much of the confusion and disagreement in Easter week chronology. Let us say, for example, that we choose to accept the narrative in the Gospel of John. Then Jesus died on the cross at the same time the Passover lambs were being sacrificed in the Temple -- that is, in the afternoon of Nisan 14. He was buried in Joseph of Arimathea's tomb before sundown on that day. The Sabbath, which began at sundown following the burial, was Nisan 15, and the third day, the day of resurrection, was Nisan 16.
But if the chronology of the synoptic Gospels is accepted, it would appear that Jesus and his disciples enjoyed their Passover meal at the start of Nisan 15 (after sundown on what we would call Thursday), and his trial, crucifixion and burial all took place on that same Jewish day (our Friday), so that the Sabbath was on Nisan 16, and the resurrection on Nisan 17. Thus the calendar sequence -- Thursday, Last Supper; Friday, crucifixion, death and burial; Sunday, resurrection -- remains the same for both accounts in our reckoning. The days in the Jewish calendar are what differ.
Well, you ask, why does it matter? The reason is that the Hebrew (not Julian) date of the crucifixion is crucial in determining the year in which Jesus died. If John is correct, Nisan 14 was on a Friday in that year; but if Matthew, Mark and Luke are correct, it was Nisan 15 that fell on a Friday. The two accounts obviously lead to different years as candidates -- and that has resulted in most of the ink that has been devoted to the controversy.
If we use the dates which Josephus tells us Pontius Pilate served in Judaea, then Jesus had to have died between the years A.D. 26 and A.D. 36. We can narrow this range down further by considering the data which St. Luke gives us. Luke, who as an historian has proved accurate in so many other things, reports that John the Baptist began his ministry in the "fifteenth year of the reign of Tiberius Caesar" (3:1), and that Jesus began his ministry when he was "about thirty years of age" (3:23), after he had been baptized by John. Historians generally agree that Tiberius' fifteenth year, in the regnal system used by Roman historians of the time, began in A.D. 29. If we allow some time between the start of John the Baptist's ministry and the start of Jesus' own, we see that the latter's crucifixion must have occurred in the latter half of the reign of Pontius Pilate, and not in the first half.
This conclusion is reinforced by the analysis done earlier here about the probable date of Jesus' birth. As we there reviewed all the latest evidence about the date of King Herod's death, and the amazing signs in the skies over Jerusalem in the years 3-2 B.C., we came to the conclusion that Jesus was probably born in early summer of 2 B.C., or perhaps as early as the fall of 3 B.C.
Adding 30 years to those dates (and remembering that there is no Year Zero in between 1 B.C. and 1 A.D.), would put the start of Jesus' ministry at the time Luke indicates, sometime after A.D. 29. If we then allow for at least three Passovers (John's Gospel) for the duration of that ministry, the range of probable dates for Jesus' death falls between A.D. 30 at the very earliest, and A.D. 34 at the latest.
This narrows the choices based on Hebrew days considerably. For Nisan 14 fell on a Friday on just two years during that period: in A.D. 30 and again in A.D. 33. (Remember, we are talking about Nisan 14 beginning after sundown the previous Thursday and continuing until sundown Friday evening, after which Nisan 15 would begin.) And -- here is what I consider to be the decisive fact -- Nisan 15 never fell on a Friday in the years A.D. 30 through A.D. 34 (unless one allows for an intercalated month, as the Babylonians -- but not always the Sadducees -- might have done). The last time it fell on a Friday was in A.D. 27, a date which is certainly too early for the crucifixion, for the reasons given above. (And if the Sanhedrin did agree to add an extra month the way the Babylonians probably did in A.D. 34, then Nisan 15 would have also been on a Friday in that year. But there is no evidence of the Sanhedrin ever having been guided in these matters by the Jews who remained in Babylon.)
The upshot of all this calendrical evidence is that there are really only two viable candidate years for Jesus' death during the reign of Pontius Pilate: A.D. 30, when Nisan 14 fell on Friday, April 7, and A.D. 33, when Nisan 14 fell on Friday, April 3. Next we ask: are there any other considerations that would allow us to choose between these two possibilities?
As noted earlier, the date of April 7, 30 A.D. is a little too close to Luke's data concerning the commencement of the ministries of John the Baptist and Jesus, respectively, and its duration (according to John) of at least three years. We would then be using Luke in part to date the crucifixion, and also relying on John's account of Jesus' ministry ending on a third Passover, rather than taking literally the other gospels' accounts, which mention only a single (albeit the final) Passover. The scales are tipped decisively in favor of A.D. 33, moreover, by two other undeniable historical facts.
The first is a seemingly remote event in Rome, which might be thought at first to have no connection to Jesus' crucifixion and death. In the last weeks of A.D. 31, Tiberius Caesar first deposed, then allowed to be killed, his tyrannical prime minister and strongman Sejanus, who was (according to Philo and Josephus) vindictively anti-Semitic. It was under his influence that Pontius Pilate committed a number of violent outrages against the Jews in the first years of his rule, as reported by Josephus. But after his death, Tiberius sent word to his governors to treat the Jews with more respect for their customs and ways. Many scholars thus argue that Pilate's vacillation in condemning Jesus was because he did not want to be embarrassed before Tiberius under this new edict, while if the trial had occurred in A.D. 30, while Sejanus was still running things, Pilate would have had no fears whatsoever on that score.
The second consideration is an astronomical one. Given the signs in the skies that attended Jesus' birth, as noted in this earlier post, it is perhaps fitting that on April 3, in A.D. 33, there was a partial lunar eclipse in Jerusalem, when the moon would have taken on a blood-reddish hue. (The eclipse began at 3 in the afternoon, but the moon would still have been below the horizon at that point; by the time it rose several hours later, there is some dispute about how red it would have remained to the naked eye.) Luke (23:44) speaks of "the sun's light having failed" (or, as some ancient manuscripts have it, "the sun was darkened") at the moment of Jesus' death, and perhaps this refers to a faint memory of what was actually a darkening of the moon (there being no way that a solar eclipse could occur on Passover, a night with a full moon).
With the account in John's Gospel thus vindicated, it becomes possible to assert, with some degree of certainty, that Jesus died on the day of preparation for Passover (Nisan 14), on April 3, in A.D. 33. (In the "nothing new under the sun" category, note that Isaac Newton had arrived at this same conclusion -- as his second choice, however -- by 1733.) If one realizes that Nisan 14 ended on that date around 6 P.M. local time, and Nisan 15 then began, it might be possible to reconcile the differences between the chronologies of John and the synoptics if the two were using different calendrical systems, and that is what a number of recent scholars indeed have argued, as Pope Benedict XVI discusses in his recent book. (One even contends that Jesus and his disciples would have been following an ancient pre-exilic calendar, where Passover would have been observed on Wednesday, April 1 in A.D. 33, even though most of Jerusalem would have observed it on Friday, April 3. This allows the Last Supper to have been a true Passover meal, while also adding another whole day for Jesus' arrest and multiple trials.)
The solution which has garnered the largest following is that reached by John P. Meier in his monumental four-volume work, A Marginal Jew: Rethinking the Historical Jesus (Vol. 1, at pp. 399 ff.). He accepts the Johannine account, according to which the Last Supper occurred at the start of Nisan 14, the day of preparation for the Passover. (However, he comes down for Nisan 14 in A.D. 30, based on his having been influenced by the traditional arguments for Jesus' birth in 4 B.C. or earlier.) In his view, Jesus realized that he would not live to celebrate the traditional Passover meal with his disciples, and so used this necessity to inaugurate the new sacrament of Holy Eucharist -- which could explain the remarks in John's narrative about Jesus not partaking of wine or bread again with his disciples "in this world". In describing the meal as a "Passover" one, therefore, the synoptic accounts conflated the old tradition with the new, as Jesus -- being the supreme Paschal lamb -- could well have intended.