Rom 13:12; 1 Pet 1:20,4:7; Heb 1:2; Jam 5:3,5:8; 1 John 2:18,4:3
You're wrong if you think these scriptures specify that Christ must return within a certain number of years (short or otherwise). They don't offer such a specific and they don't intend to fill such a purpose. Consider St. Peter: "There shall come in the last days scoffers, walking after their own lusts, and saying, 'Where is the promise of his coming?' ... But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day. The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance. But the day of the Lord will come as a thief in the night." The tenor of such scriptures is in unison with Christian thought throughout the ages: one of expectation, of hope and faith, of self-examination, of unity with brethren of all ages. St. Peter again: "What manner of persons ought ye to be in all holy conversation and godliness, looking for and hasting unto the coming of the day of God ... ? ... Wherefore, beloved, seeing that ye look for such things, be diligent that ye may be found of him in peace, without spot, and blameless. And account that the longsuffering of our Lord is salvation ... . ... But grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ. To him be glory both now and for ever. Amen." This perpetual expectation arises from belief in the words of the Lord himself: "Fear not, little flock; for it is your Father's good pleasure to give you the kingdom. Sell that ye have, and give alms; provide yourselves bags which wax not old, a treasure in the heavens that faileth not, where no thief approacheth, neither moth corrupteth. For where your treasure is, there will your heart be also. Let your loins be girded about, and your lights burning; and ye yourselves like unto men that wait for their lord, when he will return from the wedding; that when he cometh and knocketh, they may open unto him immediately. Blessed are those servants, whom the lord when he cometh shall find watching." Etc.
The liberal doctrine you hold or held that the disciples of Christ were motivated by sheer naivete in their eschatology is a product of academic cynicism toward God and mean satisfaction with supposed superior modern intelligence, not to mention the usual anti-semitic undertones.