The complete quote is:
If you tell a lie big enough and keep repeating it, people will eventually come to believe it. The lie can be maintained only for such time as the State can shield the people from the political, economic and/or military consequences of the lie. It thus becomes vitally important for the State to use all of its powers to repress dissent, for the truth is the mortal enemy of the lie, and thus by extension, the truth is the greatest enemy of the State.”
Joseph Goebbels did say it. Don't sell him short. he was an extremely intelligent man, a brilliant manipulator, and was Hitler's Master of Propaganda. Goebbels's deeply rooted contempt for humanity, his urge to sow confusion, hatred and intoxication, his lust for power and his mastery of the techniques of mass persuasion were given full vent in the election campaigns of 1932, when he played a crucial role in bringing Hitler to the centre of the political stage. He was rewarded on 13 March 1933 with the position of Reich Minister for Public Enlightenment and Propaganda, which gave him total control of the communications media - i.e. radio, press, publishing, cinema and the other arts. He retained this position for his lifetime. He was Hitler's right hand man until their deaths. He chose to suicide himself and poison his wife and 6 kids so as to die with Hitler.With characteristic pathos and egomania he declared not long before his death: 'We shall go down in history as the greatest statesmen of all time, or as the greatest criminals.'
He also said:
“The most brilliant propagandist technique will yield no success unless one fundamental principle is borne in mind constantly - it must confine itself to a few points and repeat them over and over”
Whoever can conquer the street will one day conquer the state, for every form of power politics and any dictatorship-run state has its roots in the street.”
“If the day should ever come when we [the Nazis] must go, if some day we are compelled to leave the scene of history, we will slam the door so hard that the universe will shake and mankind will stand back in stupefaction..”