The Hadith are not infallible or perfect in Islam, only the Quran is believed to be so as the word of Allah.
Where in the Quran does it say that Blasphemy should be punished by death and that Ahmadi's cannot call themselves what they please and practice their religion as they please?
And how does the Quran define Blasphemy?
Firstly,Just because of some hadiths being unreliable, you have no right to say that all hadith and sunnah are not perfect..... This Fitna was created by non muslims just to destroy the Wonderful Sunnah of our Holy Prophet (SA) . Please don't be a part of it...
Secondly Brother you should be clear that we have two sources of Law, not one.. they are
Quran and
Sunnah... Sunnah is also a law because Holy Prophet (SA) did only what was told to him by Allah.. there is a famous Ayat in Quran. i don't exactly know its source. if any one knows then please contribute here. that Ayat says:
"He (Muhammad SA) Doesn't speaks in vain. He speaks in Revelations"
Every conduct and every saying of Holy Prophet (SA) is the Law of Islam as it was ordered by Allah to Holy Prophet (SA) to be done... Holy Prophet (SA)
NEVER did anything that was against the Orders of Allah .. So if He ordered to kill the non Muslims who did such Blasphemy to Our Holy Prophet (SA) , it was according to the Will of Allah and so it is a Law of Islam...
Once Hazrat Maaz (RA) was declared Governor of Yemen by Holy Prophet (SA). Holy Prophet (SA) asked him
"How will you govern Yemen?" He replied "
By Quran."..... Holy Prophet (SA) further said; "
what will you do if you are not able to find the guidance in Quran?" he Replied "
I will consult Sunnah", Holy Prophet (SA) further enquired "
What will you do if you are not able to find the solution in Sunnah" Hazrat Maaz (RA) replied "
I will do Ijtihaad".. Holy Prophet (SA) was very Pleased with his reply and sent him to Yemen...
So the above Hadith proves that if we can't find any solution to the issue in Quran, then Shariah says us to Obey Hadith and Sunnah..
Thirdly, you enquired about Ahmedis in Quran..
By name, Ahmedis are not mentioned in Quran, because this Fitna didn't existed at the time of Prophet (SA)....
But when Quran and Holy Prophet (SA) declares, that
Prophet Muhammad (SA) is the last Prophet of Allah and their will be no Prophet after him,
then those who claims Prophethood after Prophet (SA) are all Kafir and their followers are also Kafir , because they destroyed their believe in the Finality of Prophethood of Prophet Muhammad (SA).....
If they claim themselves to be Muslims and calls their places of Worship as Masjid, it will Damage Islam Severely because it will create another false Sect in Islam that will have
A highly Significant difference in Belief...
Sunni-Shia mainly have differences about the Companions of Prophet (SA). But this Kafir sect have a difference in one of the
Most Important Belief of Islam i.e Finality of Prophethood...
If this Sect is declared as Muslims, then
We will be considering Holy Prophet (SA) as the Last Prophet , and
these people will be considering the maniac Qadyani to be their Prophet, and still they will be calling themsleves Muslims .. ... And we should recognise that
"This is not small issue. this Fitna is one of the Biggest Fitnahs of Islam"
And still if we allow them to say that they are Muslims , Then really
SHAME ON US, that we were not able to stop them from calling themselves muslims...
As far as your last question is concerned, The Holy Quran may contain such ayat, but I have no Ayat of Quran in my knowledge that defines Blasphemy... .... If any one can contribute here it will be really beneficial.