Question: Can there be a genuine case where a person denies the existence of God? If not, why do we bother having dialogues with Atheists? Is it our duty to have dialogues with the atheist on existence of God. 
    Answer: According to the Qur’an the existence of God is a reality found in the intuition of every person. There is no doubt about the fact that the perception of Creator is found in the intuition of every person. The Qur’an says that before mankind was created, the Almighty took a covenant from the spirits of all individuals about His being their Creator. At that time, all of them acknowledged this fact, which was subsequently made a part of their intuition by the Almighty. A person who still denies this fact is bound to be doomed in the Hereafter. The Qur’an says: 

When your Lord drew forth from the children of Adam from their loins their descendants and made them testify upon themselves [saying]: Am I not your Lord. They said: Yes indeed we do testify. [This was done] lest you should say on the Day of Judgement: Of this we were unaware or [you put forward the excuse] that our forefathers were idolaters and we were their descendents after them. Will you then destroy us in retribution of the misdeeds of the evil doers. (7:172-73)

    A person’s concept about God may be incorrect but as far as the question of whether there is a God is concerned, human intuition needs no external agency to point this out. Consequently divine Books only correct our conception of God by explaining His attributes and His practices. One therefore cannot have any genuine ground if one persists in denying His existence -- one can however have an incorrect perception about Him. 
    Atheists are people who are not new to this world. One can only have a dialogue with atheists if they are willing to exchange views on the basic questions of life. It is not our responsibility to convince people who are not ready to exchange views. However, if one does find an atheist who is willing to talk, then instead of talking to him on the basis of Divine Books, he should be tackled through his intuition and through the fact that without a God, the cognizance of morals found within every person cannot be explained.