What is the content of Al-Ma'arri's Risalat al-Ghufran (The Epistle of Forgiveness), and what is the ruling on reading it?

Al-Ma'arri was accused concerning his creed, and both Al-Dhahabi and Ibn Al-Jawzi described him as a heretic (zindeeq), especially due to his book "Risalat al-Ghufran" (The Epistle of Forgiveness), which contained heresy. Therefore, one must avoid reading his writings because of the deviation and atheism they contain. The Muslim is sufficed by reading the Qur'an, the Sunnah, and the sayings of the Companions.