The predominating emphasis is upon the uncertainty of the time, in the light of which people must always be ready. This is the characteristic perspective of the Old Testament prophets. The Day of the Lord is near (Isa. 56:1; Zeph. 1:14; Joel 3:14; Obad. 15); yet the prophets have a future perspective. They are able to hold the present and the future together in an unresolved tension. “The tension between imminence and delay in the expectation of the end is characteristic of the entire biblical eschatology.” “One word can sound as though the end was near, another as though it only beckoned from a distance.” This may not be the thought pattern of the modern scientifically trained mind, and the dissection of the prophetic perspective by a severe analytic criticism may serve only to destroy it. A proper historical methodology must try to understand ancient thought patterns in terms of themselves, rather than forcing them into modern analytical categories. The overall impression of the Synoptics is clear. They leave readers in a situation where they cannot date the time of the end; they cannot say that it will surely come tomorrow, or next week, or next year; neither can they say that it will not come for a long time. They keynote is: “Watch therefore, for you know neither the day nor the hour.”
George Eldon Ladd, A Theology of the New Testament rev. ed. (Grand Rapids: Eerdmans, 1993), 210-211.