What is the ruling on one who was afflicted with obsessive thoughts of insulting the Divine Essence, and uttered the insult—God forbid—unintentionally? Does this affect his marriage contract?

Satanic whispers (waswas) concerning matters of faith do not harm the one experiencing them, as long as he dislikes them. Even if he utters words of disbelief involuntarily under the influence of these whispers, he does not become a disbeliever thereby, nor does it affect his Islam or the validity of his marriage contract. It is recommended to turn away from these whispers, seek Allah's help, and engage frequently in remembrance of Allah (dhikr) and supplication (du'a).