In the answer to question no. 10160 we have quoted the words of Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him):
Similarly, if there crosses his mind any thought of impugning Allaah (may He be exalted) or impugning the Qur'aan or other kinds of kufr, he should not pay any attention to it, and it will not harm him, and even if we assume that he says such things involuntarily, there will be no sin on him. End quote.