Fair enough - you're not alone in believing his actions were in part due to what was 'embedded in his religious beliefs'.
The issue is Islamphobe (loon) argument though is that Islam is inherently violent and that this guy was trying to kill because that is what Islam teaches Muslims should do to non-Muslims. Go to eh's guru's website JihadWatch.com and the hatred is dripping off the page - and dressed up in pseudo-scholarly misrepresentations of the Quran etc.
The problem here is that the reason the numpty gave for targetting the US is explicitly retaliation for US bombings. The numpty does not align himself with loon ideology and cite hatred for non-Muslims as a reason. In fact, as with Bin Laden, they cannot find a Quranic reason for blowing up women and children and civilians in general.
When Muslims target Christians or other Muslim sects - then that clearly is a religous act of terrorism. When Baruch Goldstein killed Muslim worshippers, that was too.
Tim McVeigh blew up fellow Americans over political issues. His fellow citizen tried to do the same - but thankfully failed.
Let's remember too, the last successful suicide terrorist in America flew his plane into a federal building this year. He was white and a Catholic. His gripe was over Federal Taxes - but no one tries to link his successful terrorist attack with his religious views.