Bro..he didn't preach against the "Jahiliyah" the extremists are preaching today and falsely attributing it to Imam Muhammed Abdul Wahhab.He mainly spoke against grave worshiping and the shirk that was becoming widespread even in Mecca. And that is the "Jahiliyah" he spoke against.. today these so called "Islamist" are far from the actual teachings of Abdul Wahhab. It is they who commit Thakfeer and try to decide who is Muslim enough etc which no layman has the right to judge.