Thank you very much for stating that. That is exactly what I meant by "the biggest".
When your 12th imam reappear (as per your belief):
Imam al-Sajjad (a) is quoted as saying that "When our al-Qa'im rises, God will remove fear from the hearts of our Shiites".
Imam Muhammad b. Ali al-Baqir (peace be upon him) has replied, “For a full eight months, he will have his sword unsheathed and will kill the enemies of God until God is satisfied.” (Al-Ghaybah)
.... no more taqiyyah.
Hence, that usul al-mazhab 'twisting' is more towards taqiyyah rather than fiqh issue...
No, it does not. It is related to shubha, where it is said one can regard the mukhalifeen as Muslims due to the fact that there is a shubha on whether haqq is with the Shi'a or not.
When the Mahdi arrives, this shubha will be lifted as the mukhalifeen will have no choice but to believe - because he will be there calling to himself and to the true Islam. If they reject, they will be regarded as kafir in both dunya and akhira, as opposed to only akhira, as some scholars have stated.
I do not know why you are still trying to argue the taqiyya point. No one has ever said this.
That explanation of yours shows how short your memory is and will only invite another obvious problem:
Why the ruling for those living during "syubha period" only apply in dunya and not extended to akhira? This syubha of not knowing whether Twelverism on the haq or not, is due to your 12th Imam by going missing, not Sunnis. And you said it yourself that the syubha will be lifted when he re-appear. Hence, proof the "fault" is purely on his side.
When any Sunnis die before your imam's re-appearance, they will die together with that syubha. Nothing change. The status remain the same. So, by any stretch of imagination, the only just and fair ruling is that those Sunnis shall remain muslim and not kafir .
As for no one has ever said it is taqiyya, surely no one from your sect will ever do that. Who wants to admit that?
Hence, the only reasonable and logical answer to "muslim in this world" is taqiyyah mumbo-jumbo.
Lol. Another fascinating comment. And this is why if you are ignorant of Shi'i Fiqh, you should not speak.
"Shubha" in this case does not change your fate (Jannah or Jahannam), "shubha" in this case is related to whether someone is intentionally or non-intentionally denying an asl of the deen.
The default criteria for Islam according to scholars like Al-Khoei is belief in the shahadatayn and qiyamah. But if you intentionally deny any other part of the religion (like Salat for example), intentionally while knowing it is the correct hukm, you will he considered a kafir.
But this ruling of "shubha" does not apply to the three default beliefs that we stated as a criteria for calling someone a Muslim, which are; Tawheed, Nubuwwah (and according to some) Qiyamah.
Now, let's return to the usool. Imamah is not a criteria to default Islam (meaning being considered a Muslim in Fiqh) - but it is a criteria for actually being a Muslim in reality, and that is what you will be judged by in the akhira.
Because denial of Imamah is not any different from denial of Nubuwwah - in principle - and so when you ask me why this "shubha" is not extended to the akhira, the answer is that in the same way the kuffar cannot be excused for denial of the Prophet (s) based on "shubha", than those who deny the Imams (as) also cannot be excused.
And I already told you, your taqiyya theory does not hold up. I told you, according to this Fiqhi opinion, you can make up your own sect right now and as long as you believe in tawheed, nubuwwah, and Immamah, then you will be considered a Muslim.
This doesn't just apply to Sunnis.