The Yemeni former president is correct for the most part about the origin of modern Islamic terrorism. The Saudi Arabian regime has funded radical clerics that schooled many of the terrorists. Furthermore, the Saudi government has been complacent when it comes to fighting terrorism, and cracking down on the sources of funding for terrorists organizations.
This may seem like an obvious statement, but I think the claims of religious rites or reasons it simply a farce. Acts of terror get immediate attention in the media and those who want the attention know how they are going to get it. Take the example of Orlando. From what we know about the murderer he was not very religious or spiritual and never was. He was probably a closet homosexual who had a lot of angst built up. His claiming of ISIS prior to committing his heinous act was probably a way for him to build up his ego in the end rather than making the call and claiming he was disgruntled, closet-homosexual.
On a larger scale, ISIS leaders think that by crafting acts of terror is a way to get noticed in the media and notoriety, but really they are just trying to inflate their own egos.
The Yemeni former president is not inaccurate in his assertion that the Wahabism supported by the Al Saud regime for decades has contributed to terrorism's prevalence. However, to assert that this ideology is the origin of terrorism is just simply incorrect. Terrorism is not isolated to one religion or political ideology; terrorist organizations have formed for various purposes and causes throughout history. In the 21st century, we forget that many of the terrorism instances of the 20th century were the work of the IRA and similar European organizations.
According to Sana news agency Yemeni former president Ali Abdullah Saleh says terrorism is the offspring of Wahhabism of Al Saud regime. The war in Yemen spread during Ali Abdullah Saleh's governance. Yemen was always a fertile ground for Al Qaida, according to analysts. Al Qaida had a presence in Yemen even before it spread to the Middle East, including Iraq and Libya.