The Lamb And His Elect

John 1:29 The next day he saw Jesus coming toward him, and said, "Behold, the Lamb of God, who takes away the sin of the world! 

This verse does not say that Christ removed all sin from the world (a daily dose of reality negates that idea), nor does it say that He died for all the sins committed by all men. It does say that his death is sufficient and effectual for all whom he died for.
Regarding the elect He removes the sin of the world. 

Rev 5:
6 And between the throne and the four living creatures and among the elders I saw a Lamb standing, as though it had been slain, with seven horns and with seven eyes, which are the seven spirits of God sent out into all the earth.
7 And he went and took the scroll from the right hand of him who was seated on the throne.
8 And when he had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each holding a harp, and golden bowls full of incense, which are the prayers of the saints.
9 And they sang a new song, saying, "Worthy are you to take the scroll and to open its seals, for you were slain, and by your blood you ransomed people for God from every tribe and language and people and nation,
10 and you have made them a kingdom and priests to our God, and they shall reign on the earth." 

He only ransoms that which is His.
He did not ransom a nation, tribe or culture. He ransomed the saints FROM every tribe, language, people and nation. They are a new nation/kingdom. 

1Peter 2:9 But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light.  ("chosen"; eklektos, i.e.the elect.)