rest of the world, but "radical christianity" is nowhere near the problem here as radical islam. If you want to say white supremacist / nationalist / neo-nazi terrorist groups are as big a problem here as radical islam, I'd still disagree, but I think you could at least make a non-laughable case.

Here's an article by the Cato institute that classifies terrorist attacks on US soil from 1992-1997. of the 3,342 people murdered by terrorists on US soil, 92% were murdered by radical islamic terrorists, and 7% were murdered by right wing/nationalists. The leftists have some catching up to do at just 1%. Obviously 9/11 skews the results for deaths attributed to radical islamic terrorists, but the OKC bombing skews the results for right wing / nationalist terrorist deaths. If you exclude 9/11 and OKC, radical islam is still responsible for 2x as many deaths as right wing / nationalist groups. And I think the threat of another big, 9/11 style attack is far greater from islamic extremists than from right wing nationalists.