The quickest answer to this is found in Matthew 24:36–44 where Jesus Himself tells us no one knows when He will return.
Is Jesus Christ going to return in 2017? Is 2017 a Jubilee year?
Still, for centuries people have predicted dates and years and times and seasons for His return. Quite obviously, the overwhelming majority of these predictions have been incorrect. Other predicted dates simply haven't occurred yet, but we can be reasonably certain they are incorrect since Jesus clearly said no one would know. Some believe 2017 to be a year of Jubilee and want to connect that to Jesus' return.
The Old Testament gave instructions for the Israelites to, every 50 years, observe a Jubilee—a year of celebration, rejoicing, rest, and release from debt (Leviticus 25:8–55). In the seventh month of the forty-ninth year, on the tenth day of the Jewish calendar, Jubilee would be ushered in with the sound of a loud trumpet. A little math would show us that there have been about 39 years of Jubilee in the past 2,000 years. The next one could be the 40th, and with 40 being a number used in the Bible, some believe this is the time for Jesus to return.
The year 2017 was first identified by an ancient rabbi, Judah ben Samuel, who predicted that the savior would return during a year of Jubilee. He calculated in AD 1217 that 2017 would be the year based on the number of years of Jubilee. He said the Savior would appear again during the Feast of Tabernacles (Sukkot) which falls from October 4–11, 2017. However, the celebration and observance of years of Jubilee ceased when the northern tribes of Israel were carried off to Assyria in 722 BC. So, now what? No year of Jubilee, no return of Jesus during a year of Jubilee?
Also, some Jewish sources say there can be no year of Jubilee observance without the Sanhedrin. There has not been a Sanhedrin since AD 70 when the second temple was destroyed by the Romans.
To make this prediction even more improbable is what the Bible says about Jesus' Kingdom. It says that the establishment of the kingdom will come after seven years of tribulation. That has not happened. The man of lawlessness must reign for at least three and half years (2 Thessalonians 2:3–8), so 2017 cannot be the end of that period of time either.
Of course, as Jesus stated, the time of His return is not known by anyone, so it could be today, or tomorrow, or in 2017. Little good it does us to try to figure it out. These energies can be put toward drawing close to Jesus, keeping watch (Matthew 25:13), and telling others the Good News of the gospel.
When is Jesus coming back?
Jesus will return like a thief in the night, what does that mean?
Will Jesus come in the clouds? What does Revelation 1:7 mean?
Is the return of Christ truly imminent?
Why didn't Jesus come back during the blood-red moon of 2015?
Truth about the End Times