"Muslims cannot fight under the banner of kuffar or with them; Muslims must avoid attaching themselves to nation states; Muslims must avoid harming and fighting other Muslims."

"Websites denounce British Muslim soldiers," by Duncan Gardham in the [1] Telegraph, with thanks to Ruth King:

The question of British Muslims joining the Army, said to have been a key issue behind the suspected Birmingham beheading plot, has been buzzing around the internet....

On another site, Mahmud Abdul Baari, a follower of the exiled preacher Omar Bakri Mohammed, called Hashmi a terrorist, adding: "Although born Muslim [he] grew up to become an apostate traitor to Islam and professional terrorist who unlike members of al-Qa'eda took a salary."...

A fatwa [religious ruling] by a man calling himself Afdal al-Jihad and posted on a mainstream web community is titled "Muslims serving in an Army of Kuffar" [non-believers]. Al-Jihad says: "Muslims cannot fight under the banner of kuffar or with them; Muslims must avoid attaching themselves to nation states; Muslims must avoid harming and fighting other Muslims."

On a web forum called the Muslim Public Affairs Committee, not all the visitors agreed that it was un-Islamic to join the Army. But many said swearing allegiance to the Queen was against Islam.