If a muslim commits blasphemy is it forgivable?

Assalaam alai'kum,


I was told that if a muslim commits blasphemy whether he/she did it intentionally or unintentionally , they must say the shahada again. I've researched left and right and could not find anything about this certain matter. Non of this makes sense because when we end our Salah with At-Tahiyyato we do say the Shahadah in every Salah. Its like we're becoming muslims again everytime we say the Shahada. So I do not understand why this teacher has been telling me this. I hope you can help me to find the answer to this insh'allah!

Walaikum assalam wa rahmatullah,

I pray that this finds you well, and in the best of health and spirits. May Allah grant you all good and success in this life and the next.

[1] It is not a simple matter to leave Islam: only denying those matters on must believe to enter Islam causes one to leave Islam--Allah won't send a believer to Hell, eternally, on a mere technicality.

[2] Yes, if someone did leave Islam, they'd need to re-enter it. The profession of faith in the prayer--and, according to many scholars, the act of prayer itself--are a sufficient statement of faith.

And Allah alone gives success.

Faraz Rabbani