What is the response to a professor who claims that Paradise is nothing but a matter of laziness and idleness?

Belief in Paradise is part of belief in the Last Day, which is a pillar of faith. Denying it constitutes disbelief. Paradise is Allah's reward for His righteous servants, and in it there is what no eye has seen, no ear has heard, and no human heart has conceived. A sound mind recognizes its wisdom and its effect on a servant's diligence and patience. This must be clarified to anyone who denies Paradise or doubts it, and that belief in Allah and His Messenger necessitates belief in the Qur'an and the Sunnah and what they contain. If one does not believe in Allah, then the way forward is to prove the existence of Allah and the prophethood of His Prophet. This dialogue should be conducted by those qualified to discuss with atheists.