Preterism is the view that all prophecy fulfillment is now past. This includes the great tribulation, the day of vengence, the resurrection of the dead, the second coming of Christ and the fulness of the kingdom of God.
A preterist is one who believes these things based on the time texts of Scripture. The reasoning that the NT writers were preparing the 1st century church for the Day of the Lord.
Preterism contains in its point of view that the heavens and the earth taught as passing away represented the Old Covenant system. We are now in the new heavens and new earth (New Covenant system).
The term "Preterist" is taken from the Hebrew language's "Preterite" tense, which is the "past perfect" sense, in terms of once for all completion or accomplishment. When applied to Bible Prophecy, the term has reference to events being fulfilled (completed, accomplished) in the past.
Here is just one of the many numerous passages that reveal when the "second coming" of Christ was to take place. This is the context: Jesus is the speaker of this passage, and His audience is His twelve disciples who are standing in front of him (Matthew 16:5-6,13,20-21,24). Put yourself in the place of those being addressed 2,000 years ago.
Matthew 16:27-28, "For the Son of man is about to come in the glory of his Father with his angels; and then he shall reward every man according to his works. Verily I say unto you, There are some of those standing here, who in no wise shall taste of death, until they have seen the Son of man coming in his kingdom."
Notice how Jesus said that some of his disciples, who were standing right there in front of him, would not die until He came with his angels to reward every man according to his works (Revelation 22:12). But since this contradicts the belief that Jesus will come sometime in our future, many try to come up with excuses why this passage does not mean what it says.