Assalamualaikum. If someone brings a blasphemous sentence to mind not with the intention of approving it but with the intention of enjoying it. Would he exit the fold of Islam in that case? Would he commit major sin only? Please read this two articles in https://questionsonislam.com/
Fifth Aspect: The scruple related to the issues of belief.
4- The delusion coming in the form of doubt regarding issues of belief.