Mufaddal bin 'Umar al-Jau`fi wrote a letter to Hazrat Imam Jafar al-Sadiq (A) that some people held the No Allah theory and contested among themselves with groundless arguments. He requested the Imam (A) to refute these atheists, as he (the Imam) had done on previous occasions. The Imam replied, In the name of the Most Merciful and the Most Compassionate Allah. May He the Almighty give us the good sense of ever remaining obedient to His will, drawing down upon us His pleasure and mercy.
Your letter with reference to those evils that have crept into our midst is in our hands You mention that these 'atheistical disputes' and controversies have become a menace to our religion (Islam), and you desire me to publish a book in condemnation and contradiction of them, as I have done (for antagonists and opponents of Allah) before.
Let us offer our thanks to Allah-the Most High for all His blessings to us, and for His Hujjat (proof) incomparable, and the justice of trial with which he tests His favorite as well as His ordinary slaves. One of the greatest and most important favors from Him is the establishment of convincing proof-deep in the innermost heart of each creature that 'He is'.