Didn't Jesus say that he would return soon? In this case, Jesus said something would happen shortly, but it hasn't happened for over 2,000 years. What would be the difference between these two statements?
In a discussion related to the destruction of Jerusalem, Jesus did promise that he would bring that destruction within the generation of his audience. "Now learn this parable from the fig tree: When its branch has already become tender and puts forth leaves, you know that summer is near. So you also, when you see all these things, know that it is near -- at the doors! Assuredly, I say to you, this generation will by no means pass away till all these things take place" (Matthew 24:32-34). However, he follows this with a discussion of his second coming, which he states will not have advanced signs. "But of that day and hour no one knows, not even the angels of heaven, but My Father only. But as the days of Noah were, so also will the coming of the Son of Man be. For as in the days before the flood, they were eating and drinking, marrying and giving in marriage, until the day that Noah entered the ark, and did not know until the flood came and took them all away, so also will the coming of the Son of Man be" (Matthew 24:36-39).
Jesus also said that a time of testing was coming quickly for those in Philidelphia, "Because you have kept the word of My perseverance, I also will keep you from the hour of testing, that hour which is about to come upon the whole world, to test those who dwell on the earth. I am coming quickly; hold fast what you have, so that no one will take your crown" (Revelation 3:10-11). Jesus also warned that he would bring about the prophecies in Revelation quickly (Revelation 22:7,12,20), but it is a mistake to see Revelation as talking solely about Jesus' second coming.
What many people overlook is that Jesus gave many hints that he would be gone for a long time.
"But if that evil slave says in his heart, 'My master is not coming for a long time,'" (Matthew 24:48).
"But while the bridegroom was delayed, they all slumbered and slept" (Matthew 25:5).
"After a long time the lord of those servants came and settled accounts with them" (Matthew 25:19).
"And He began to tell the people this parable: "A man planted a vineyard and rented it out to vine-growers, and went on a journey for a long time"" (Luke 20:9).
Time doesn't have the same meaning for the eternal God as it does for mortal man. "Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts, and saying, "Where is the promise of His coming? For ever since the fathers fell asleep, all continues just as it was from the beginning of creation." ... But do not let this one fact escape your notice, beloved, that with the Lord one day is like a thousand years, and a thousand years like one day. The Lord is not slow about His promise, as some count slowness, but is patient toward you, not wishing for any to perish but for all to come to repentance. But the day of the Lord will come like a thief, in which the heavens will pass away with a roar and the elements will be destroyed with intense heat, and the earth and its works will be burned up" (II Peter 3:3-4,8-10). The Lord's return might be long, but when it does occur, it will be sooner than mankind expects.
The reason there are numerous verses warning Christians to be watchful and alert is because we can easily fool ourselves into believing we have plenty of time to change our lives. "But you, brethren, are not in darkness, that the day would overtake you like a thief; for you are all sons of light and sons of day. We are not of night nor of darkness; so then let us not sleep as others do, but let us be alert and sober" (I Thessalonians 5:4-6).