If islam is 1400 years old and wahabism ignores the past 1000 years old then isn't it closer to the religion of mohammed? That seems to be the core of their argument and looking at the correlation of the behaviour of al baghdadi and his followers and mohammed and his I find that a hard argument to refute.
I was writing that in a hurry so I said that in a confusing way. I meant that they are 200 years old and they ignore the first 1000+ years. Their books rarely cite classical scholars, in preference to citing a small number of Wahhabi scholars (Ibn Abd al-Wahhab, Hamad ibn Atiq, Nasruddin al-Albani, Abdul-Aziz bin Baz, ibn Uthaymeen). Though to be fair, ISIS even rejects most of those scholars because they were associated with the Saudi State (which they regard as in a state of apostasy). They even reject the even smaller number of "Salafi-Jihadi" scholars like Abu Qatadah and Shaykh al-Maqdisi because those scholars sided with Al-Qaeda in the dispute between AQ and ISIS. ISIS has no scholarly backing whatsoever, even from the marginal Wahhabi tradition. They're literally a bunch of teens and 20-somethings who can't read classical Arabic making up religious rulings on the fly.
The traditonalist Sunni position is that Wahhabis have an extreme lack of reverence for the Prophet (sallallahu alayhi wa sallam). In a recent debate in England, a Salafi preacher compared the Prophet (sallallahu alayhi wa sallam) compared the Prophet (sallallahu alayhi wa aalihi wa sallam) to a dead dog. A few years back an ISIS spokesman said that if the Prophet (sallallahu alayhi wa aalihi wa sallam) were alive, he'd have to follow them. This is why traditionalist Sunnis in Pakistan often refer to Wahhabis as the "Gustakh-e-Rasul" (Revilers of the Messenger).
When you actually study the corpus of authentic Sunni ahadith, the actions of ISIS don't resemble those of the Prophet (sallallahu alayhi wa aalihi wa sallam) or the ashab al-kiram, they resemble the acts of the Khawarij (the early dissident group that assassinated the Fourth Rightly Guided khalifah, Mawla Ali al-Murtadha, karramallahu wajhu), or the illegimate Umayyad ruler, Yazid (who murdered the Prophet's grandson, Sayyidina al-Husayn, alayhis salam, and his family). The Prophet (sallallahu alayhi wa aalihi wa sallam) laid down rules for warfare, and ISIS has never followed any of them. They don't respect the shari'ah in that case or in any other.
If you are a traditionalist Sunni, do you agree gays, adulteresses and idol worshippers should be put to death under sharia law?
As for gays, I'm a Hanafi, so I don't believe sodomy carries a death penalty. It carries a ta'zir punishment, which is determined by a judge and can be corporal punishment of up to ten lashes, imprisonment, or exile.
As for adultery, the hukm is that both adulterers and adulteresses are stoned to death.
As for idol worshippers, according to the majority of classical jurists (mostly of the Hanafi and Maliki schools), there is nothing entailing a death penalty on any idol worshipper who does not make war with the Muslims. The command to kill idolators is restricted to the idolators of the Arab peninsula of the time of the Prophet (sallallahu alayhi wa sallam). Non-Arab idolators who are conquered by Muslims are allowed to pay the jizyah just as the Ahl al-Kitab are (this is what happened to the Hindus in Mughal India). However, the definition of idolator is debatable, and some of the classical jurists actually argued that the Hindus (and Jains and Buddhists) were not idol-worshippers, but were people of the book because they possessed scriptures. This as based on an analogy with how the Zoroastrians or Iran had been regarded.