The alleged mastermind of the September 11 terrorist attacks has written a rambling, deeply religious manifesto that suggests Muslims should not use violence to spread Islam - a sharp departure from his earlier boasts of waging jihad against the US and other non-Muslim nations. The unclassified comments by Khalid Sheikh Mohammed, who will soon turn 50 and has spent the last decade in US custody, come a year-and-a-half into the pre-trial phase of his military commission trial. The writings suggest he either believes he can convert his US audience or, as he often has done, is trying to attract publicity, feign mental illness or spare himself the death penalty if convicted of playing a role the 2001 attacks. The 36-page document, titled "The Road to Real Happiness", includes not only references to the Koran, but quotes by former US presidents Richard Nixon and George W.Bush and Pope Benedict XVI. Mohammed rails against same-sex marriage, abortion and the moral decay of the West. He mocks US soldiers for playing with their PlayStations in Iraq and Afghanistan while Muslim families struggle for food and shelter. "But at the end the American soldiers go back home and commit suicide but the poor man still with his dry bread and black tea lives with his poor wife in their humble muddy house but with happy hearts and souls," he wrote. The document is described as the first of three parts, with subsequent writings to defend the September 11 attacks and dispute the validity of the US-led invasions of Iraq and Afghanistan, which he suggests were chiefly meant to benefit military contractors such as Halliburton. The Koran, Mohammed wrote, "forbids us to use force as a means of converting" others, and "truth and reality never comes by muscles and force but by using the mind and wisdom". Those statements clash with his earlier braggadocio in saying he plotted the September 11 attacks and personally beheaded The Wall Street Journal reporter Daniel Pearl, and in calling for Muslims to embrace violence. Pentagon officials said Mohammed wrote the document last October and asked that copies be hand-delivered to the court officials via his defence team. Mohammed was captured in 2003. After three years of custody at so-called CIA black sites, where he was repeatedly waterboarded, he was transferred to the US prison at Guantanamo Bay in 2006.