The 16th episode of Mark Goodacre’s NT Pod shows that there is no evidence within the Gospels themselves (or the New Testament itself) that Jesus’ ministry was three years (or 3 1/2 years), as is often assumed in devotional or traditional literature, movies, etc.
Goodacre points to Origen (3rd Century) and Eusebius (4th Century) as the earliest sources for the idea that Jesus’ ministry was three and a half years, each of whom take their cues from Daniel to determine the length of Jesus’ ministry, but he doesn’t get into the details of the passage that governs their timetables.
From Origen and Eusebius, it’s clear that the notion of a 3 1/2 year ministry stems from an early Christological interpretation of Daniel 9:26–27, which talks about an “anointed one” being cut off “after the sixty two sevens” (the 62 sevens follow seven earlier sevens, making it after the 69th seven overall; these “sevens” seem to have been identified as groups of seven years, though it’s not clear whether Jubilee years are factored in as well) and putting an end to sacrifice and offering “in the middle of the final seven.” This “being cut off” and putting the end of sacrifice and offering were identified as the crucifixion, which would have happened in the middle of the final (70th) “seven,” or three and a half years after an “anointed one” shows up at the end of the 69th seven. Thus, reasoned Origen and Eusebius, Jesus’ ministry must have commenced at the beginning of the 70th “seven,” and the crucifixion must have been 3.5 years into that ministry.
I’ve long thought that the “70 sevens” passage in Daniel 9 was a major factor in the messianic fervor of the first century BCE through the early second century CE, as the Jews of that period expected the prophecy to be fulfilled in their time. That Origen and Eusebius continue to use Daniel 9 as a source for the ministry of Jesus in the third and fourth centuries only underscores my conviction on this point.
It’s also worth pointing out the somewhat amusing reversal this terse passage in Daniel 9 has undergone in popular theology over the last century. These verses went from being understood as a prophesy of the ministry of Jesus (as in Origen and Eusebius) to being interpreted as prophecies of the antichrist in modern dispensational theology. In that theological scheme, the “70th seven” is still to be fulfilled in the future by the antichrist, who will be the one to “put an end to sacrifice and offering,” etc., during the “Great Tribulation” (i.e. the “70th seven,” which oddly has no temporal link to the other 69 “sevens). You’d probably have to have been in a coma the last few years not to have seen or heard about the “Left Behind” series, which is based on this popular theology, all of which rests on this understanding of the “70th seven” as a future seven-year “Great Tribulation.”
So the same passage has been alternately interpreted as prophesying Jesus’ ministry (in the earliest Christian interpretation) or as predicting the reign of the antichrist. Amazing how flexible such obscure and difficult prophetic passages can be, no?