What does this mean: "The Day of the Lord" ?

Many people don't understand this phrase:

The Day of the Lord

What does it mean? Some esoteric "chist-consciousness" coming to earth to make everyone more loving, educated, and highly evolved?

Well, as for me, I think of a song:

I will serve Him because I love Him
He has given life to me
I was nothing 'til Jesus found me
He has given life to me

Heartache, broken pieces, ruined lives is why
He died on Calvary
His love is all I long for
He has given life to me

Even in some nominal Christian circles, people don't understand "the day of the Lord." In the Bible, it is one good day for those who love this Savior they have yet to see. It is all detailed in the book of Revelation. It is a far better day--the "revelation" of Jesus Christ--than the G-20 summit could ever dream or configure. It is better than any human accomplishment, such as the social harminization of the world. This is the Day when Jesus will be revealed in all of His glory, and when those who never believed will bow. It seems strange to those with antipathy toward Him in this world and too extreme to believe. For the follower of Jesus, it also seems strange--that He would ever love us the way He really does and that the whole story of Jesus and His crucifixion and resurrection is actually true. Oh, but our faith is not blind! He has poured out His love within our hearts with peace that the "prince of the power of the air" cannot counterfeit. The best thing of all is that He is the only God pure with no lie in Him. What a joy to call such a God mine and to know that He is making me more like Him, delighting in my need for Him. I shudder when I think of where I'd be without Him.

With a faithful Shepherd who loves me so much,
Dwayna