At the core of the New Testament world is one central idea and it's expressed as more of a concern: At a given moment in time, the resurrected Jesus of God will come back to earth yet again, not as a savior but as a judge.  It will be a time of final reckoning when God's ultimate justice will be meted out to saints and sinners alike.  This concern pops up all over the place: The disciples are often quizzing Jesus as to the time and place, Paul frequently admonishes the recipients of his letters to always be in a state of preparedness, the post-Pentecost Peter sounds the warning, and the final book of the Christian Bible, Revelation, is its apocalyptic promise.  Truth be told, it doesn't seem to have happened just yet, at least not in a cataclysmic fashion.  But what if it really does happen?  How will Jesus judge us as a nation, as a supposedly Christian people?  Should he swing by tomorrow, what will he say about water-boarding and rendition?  What will Jesus say about torture?  What will he say about complacent Christians?  What will he say about the ways in which we "celebrate" his birthday?  More to the point, what will we say to him if he asks us, "What do you think I died for?"

The idea and concern of the coming of God's Messiah who would mete out God's righteousness and justice didn't begin with the New Testament, however.
It was much older than that and has its roots in the Old Testament prophets,
another time of warring nations, corrupt politics, and bankrupt religion.  Such prophets also preached about "getting ready" for the Messiah, and for them, it included the willingness to lay down arms and embrace peace.  As a nation of supposed Christians, we need to be reminded of this-unless we don't want to be bothered with God and God's word.  Isaiah tells us God will "judge between the nations, and shall arbitrate for many peoples; they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war anymore."  Isaiah's advice?  "O house of Jacob, come, let us walk in the light of the Lord!"

 

The word that Isaiah son of Amoz saw concerning Judah and Jerusalem.

In days to come
   the mountain of the Lord’s house
shall be established as the highest of the mountains,
   and shall be raised above the hills;
all the nations shall stream to it.
   Many peoples shall come and say,
‘Come, let us go up to the mountain of the Lord,
   to the house of the God of Jacob;
that he may teach us his ways
   and that we may walk in his paths.’
For out of Zion shall go forth instruction,
   and the word of the Lord from Jerusalem.
He shall judge between the nations,
   and shall arbitrate for many peoples;
they shall beat their swords into ploughshares,
   and their spears into pruning-hooks;
nation shall not lift up sword against nation,
   neither shall they learn war any more.

O house of Jacob,
   come, let us walk
   in the light of the Lord!

 

A Song of Ascents. Of David.

I was glad when they said to me,
   ‘Let us go to the house of the Lord!’
Our feet are standing
   within your gates, O Jerusalem.

Jerusalem—built as a city
   that is bound firmly together.
To it the tribes go up,
   the tribes of the Lord,
as was decreed for Israel,
   to give thanks to the name of the Lord.
For there the thrones for judgement were set up,
   the thrones of the house of David.

Pray for the peace of Jerusalem:
   ‘May they prosper who love you.
Peace be within your walls,
   and security within your towers.’
For the sake of my relatives and friends
   I will say, ‘Peace be within you.’
For the sake of the house of the Lord our God,
   I will seek your good.

 

But about that day and hour no one knows, neither the angels of heaven, nor the Son, but only the Father.  For as the days of Noah were, so will be the coming of the Son of Man.  For as in those days before the flood they were eating and drinking, marrying and giving in marriage, until the day Noah entered the ark, and they knew nothing until the flood came and swept them all away, so too will be the coming of the Son of Man.  Then two will be in the field; one will be taken and one will be left.  Two women will be grinding meal together; one will be taken and one will be left.  Keep awake therefore, for you do not know on what day your Lord is coming.  But understand this: if the owner of the house had known in what part of the night the thief was coming, he would have stayed awake and would not have let his house be broken into.  Therefore you also must be ready, for the Son of Man is coming at an unexpected hour.

 

Besides this, you know what time it is, how it is now the moment for you to wake from sleep. For salvation is nearer to us now than when we became believers; the night is far gone, the day is near. Let us then lay aside the works of darkness and put on the armour of light; let us live honourably as in the day, not in revelling and drunkenness, not in debauchery and licentiousness, not in quarrelling and jealousy.  Instead, put on the Lord Jesus Christ, and make no provision for the flesh, to gratify its desires.