The next day, he saw Jesus coming to him, and said, "Behold, the Lamb of God, who takes away the sin of the world!
In this first announcement of the great office of the Son of God, it was his relation to man's sin that was emphasized.  He "taketh away the sin of the world!"  Christ did not come to solve the political problems of Israel, nor to break the back of Roman tyranny, nor for bringing improvements in agriculture, trade, medicine, or education, nor for any similar thing. Christ came to redeem people from sin.  This is the only problem incapable of solution by the race of man; but this problem is so malignant and pervasive that it requires to be solved first, before the final solution of all the other problems can be achieved, thus being the one great need of mortal man that it should be truly solved.