If a Muslim were to write an Islamic version of 'Glorious Appearing' and publish it in Saudi Arabia, jubilantly describing a massacre of millions of non-Muslims by God, we would have a fit. We have quite properly linked the fundamentalist religious tracts of Islam with the intolerance they nurture, and it's time to remove the motes from our own eyes.
By Kristof's description the last book in the series is sick, brutal, and ugly. The cult of Left Behind has created an "alternate Jesus" who would be very comfortable in the Old Testament, and completely antithetical to the New Testament. These writings legitimize any act of cruelty against the unbeliever -- who are unworthy of compassion.
These are Bush's Crusaders, and he cannot part from them.