Takfiris firmly believe that the end justifies the means. But Islam never approves of such actions as it never issues such fatwa and their beliefs are rejected by almost all prominent contemporary Islamic scholars. As an Islamic term jihad means "the struggle for God's sake." It is through jihad that every Muslim is required to defend his or her country against any foreign invader. In recent years the term has been widely misused in the media to describe bombings, suicide attacks, or any other sort of aggressive behavior by extremists.
But what exactly is jihad and when does it become obligatory for Muslims? Islam prescribes war only in certain circumstances and only religious scholars know what the circumstances are. Religious leaders must issue a fatwa when the circumstances demand jihad. But jihad doesn't mean that anyone can pick up a weapon at will and take control of a place and kill people, or make suicide bomb attack thinking it's jihad. Jihad is prescribed under certain conditions and the fatwa must be endorsed by the majority of religious scholars, not by those with personal interests and biased attitudes.
There is no religious permission or convincing reason for suicide bomb attacks that take the lives of people, whether Muslims or infidels. These acts have root in Takfiri ideology. Takfiris are a group of extremists whose names and crimes are always in the news headlines and they're infamous for their extremely violent behavior. But what is Takfiri and what do Takfiris do?
Most of the time they brand other Muslims as unbelievers or kafirs on the slightest thing which makes Takfiri style the worst one in the world of Islam. Takfirism is an offshoot of Salafism whose followers seek to get to the origins of Islam, but based on their own facile and fallacious reading. A little knowledge is a dangerous thing and that's what Takfiris are suffering from. Warning: Very graphic content.